Chapter I · THE IDEA OF PHILOSOPHY IN GENERAL. THE ORIGINS AND DEVELOPMENT OF GREEK PHILOSOPHY (continued 4)

If we are to study Plato intelligently, it is essential that we should cease to regard the dialogues as if they were all produced en bloc from a single phase of their author's mind. His literary activity extended over a period of not less than fifty years. During that time, he did not stand still. His thought, and his mode of {172} expression, were constantly developing. If we are to understand Plato, we must obtain some clue to enable us to trace this development. And this means that we must know something of the order in which the dialogues were written. Unfortunately, however, they have not come down to us dated and numbered. It is a matter of scholarship and criticism to deduce the period at which any dialogue was written from internal evidences. Many minor points are still undecided, as well as a few questions of importance, such as the date of the "Phaedrus," [Footnote 11] which some critics place quite early and some very late in Plato's life. Neglecting these points, however, we may say in general that unanimity has been reached, and that we now know enough to be able to trace the main lines of development.

The dialogues fall into three main groups, which correspond roughly to the three periods of Plato's life. Those of the earliest group were written about the time of the death of Socrates, and before the author's journey to Megara. Some of them may have been written before the death of Socrates. This group includes the "Hippias Minor," the "Lysis," the "Charmides," the "Laches," the "Euthyphro," the "Apology," the "Crito," and the "Protagoras." The "Protagoras" is the longest, the most complex in thought, and the most developed. It is probably the latest, and forms the bridge to the second group.

All these early dialogues are short and simple, and are still, as regards their thought, entirely under the influence of Socrates. Plato has not as yet developed {173} any philosophy of his own. He propounds the philosophy of Socrates almost unaltered. Even so, however, he is no mere plagiarist. There are throughout these dialogues evidences of freshness and originality, but these qualities exhibit themselves rather in the literary form than in the philosophical substance. We find here all the familiar Socratic propositions, that virtue is knowledge, is one, is teachable; that all men seek the good, but that men differ as to what the good is; that a man who does wrong deliberately is better than a man who does it unintentionally; and so on. Moreover, just as Socrates had occupied himself in attempting to fix the concepts of the virtues, asking "what is prudence?", "what is temperance?", and the like, so in many of these dialogues Plato pursues similar inquiries. The "Lysis" discusses the concept of friendship, the "Charmides" of temperance, the "Laches" of bravery. On the whole, the philosophical substance of these early writings is thin and meagre. There is a preponderance of incident and much biographical detail regarding Socrates. There is more art than matter. Consequently, from a purely literary point of view, these are among the most charming of Plato's dialogues, and many of them, such as the "Apology" and the "Crito," are especially popular with those who care for Plato rather as an artist than as a philosopher.

The second group of dialogues is generally connected with the period of Plato's travels. In addition to the influence of Socrates, we have now the influence of the Eleatics, which naturally connects these dialogues with the period of the philosopher's sojourn at Megara. But it is in these dialogues, too, that Plato for the first time {174} develops his own special philosophical thesis. This is in fact his great constructive period. The central and governing principle of his philosophy is the theory of Ideas. All else hinges on this, and is dominated by this. In a sense, his whole philosophy is nothing but the theory of Ideas and what depends upon it. It is in this second period that the theory of Ideas is founded and developed, and its relationship to the Eleatic philosophy of Being discussed. We have here the spectacle of Plato's most original thoughts in the pangs of childbirth. He is now at grips with the central problems of philosophy. He is intent upon the thought itself, and cares little for the ornaments of style. He is struggling to find expression for ideas newly-formed in his mind, of which he is not yet completely master, and which he cannot manipulate with ease. Consequently, the literary graces of the first period recede into the background. There is little incident, and no humour. There is nothing but close reasoning, hard and laborious discussion.

The twin dialogues, "Gorgias" and "Theaetetus" are probably the earliest of this group. They result in nothing very definite, and are chiefly negative in character. Plato is here engaged merely in a preparatory clearing of the ground. The "Gorgias" discusses and refutes the Sophistic identification of virtue and pleasure, and attempts to show, as against it, that the good must be something objectively existent, and independent of the pleasure of the individual. The "Theaetetus," similarly, shows that truth is not, as the Sophists thought, merely the subjective impression of the individual, but is something objectively true in itself. The other {175} dialogues of the group are the "Sophist," the "Statesman," and the "Parmenides." The "Sophist" discusses Being and not-being, and their relationship to the theory of Ideas. The "Parmenides" inquires whether the absolute reality is to be regarded, in the manner of the Eleatics, as an abstract One. It gives us, therefore, Plato's conception of the relation of his own philosophy to Eleaticism.

The dialogues of the third group are the work of Plato's maturity. He has now completely mastered his thought, and turns it with ease in all directions. Hence the style returns to the lucidity and purity of the first period. If the first period was marked chiefly by literary grace, the second by depth of thought, the third period combines both. The perfect substance is now moulded in the perfect form. But a peculiarity of all the dialogues of this period is that they take it for granted that the theory of Ideas is already established and familiar to the reader. They proceed to apply it to all departments of thought. The second period was concerned with the formulation and proof of the theory of Ideas, the third period undertakes its systematic application. Thus the "Symposium," which has for its subject the metaphysic of love, attempts to connect man's feeling for beauty with the intellectual knowledge of the Ideas. The "Philebus" applies the theory of Ideas to the sphere of ethics, the "Timaeus" to the sphere of physics, and the "Republic" to the sphere of politics. The "Phaedo" founds the doctrine of the immortality of the soul upon the theory of Ideas. The "Phaedrus" is probably to be grouped with the "Symposium." The beauty, grace, and lucidity of the style, and the fact that it assumes throughout that {176} the theory of Ideas is a thing established, lead us to the belief that it belongs to the period of Plato's maturity. Zeller's theory that it was written at the beginning of the second period, and is then offered to the reader as a sort of sweetmeat to induce him to enter upon the laborious task of reading the "Sophist," the "Statesman," and the "Parmenides," seems to be far-fetched and unnecessary. [Footnote 12]

If the second is the great constructive period of Plato's life, the third may be described as his systematic and synthetic period. Every part of his philosophy is here linked up with every other part. All the details of the system are seen to flow from the one central principle of his thought, the theory of Ideas. Every sphere of knowledge and being is in turn exhibited in the light of that principle, is permeated and penetrated by it.

The plan for expounding Plato which first suggests itself is to go through the dialogues, one by one, and extract the doctrine of each successively. But this suggestion has to be given up as soon as it is mentioned. For although the philosophy of Plato is in itself a systematic and coherent body of thought, he did not express it in a systematic way. On the contrary, he scatters his ideas in all directions. He throws them out at random in any order. What logically comes first often appears last. It may be found at the end of a dialogue, and the next step in reasoning may make its appearance at the beginning, or even in a totally different dialogue. If, therefore, we are to get any connected view of the system, we must abandon Plato's own order of exposition, and piece the thought together for ourselves. We must begin {177} with what logically comes first, wherever we may find it, and proceed with the exposition in the same manner.

A similar difficulty attends the question of the division of Plato's philosophy. He himself has given us no single and certain principle of division. But the principle usually adopted divides his philosophy into Dialectic, Physics, and Ethics. Dialectic, or the theory of Ideas, is Plato's doctrine of the nature of the absolute reality. Physics is the theory of phenomenal existence in space and time, and includes therefore the doctrine of the soul and its migrations, since these are happenings in time. Ethics includes politics, the theory of the duty of man as a citizen, as well as the ethics of the individual. Certain portions of the system, the doctrine of Eros, for example, do not fall very naturally into any of these divisions. But, on the other hand, though some dialogues are mixed as to their subject matter, others, and those the most important, fall almost exclusively into one or other division. For example, the "Timaeus," the "Phaedo," and the "Phaedrus," are physical. The "Philebus," the "Gorgias," and the "Republic," are ethical. The "Theaetetus," the "Sophist," and the "Parmenides," are dialectical.

2. The Theory of Knowledge.

The theory of Ideas is itself based upon the theory of knowledge. What is knowledge? What is truth? Plato opens the discussion by telling us first what knowledge and truth are not. His object here is the refutation of false theories. These must be disposed of to clear the ground preparatory to positive exposition. The first such false theory which he attacks is that knowledge {178} is perception. To refute this is the main object of the "Theaetetus." His arguments may be summarized as follows:--

(1) That knowledge is perception is the theory of Protagoras and the Sophists, and we have seen to what results it leads. What it amounts to is that what appears to each individual true is true for that individual. But this is at any rate false in its application to our judgment of future events. The frequent mistakes which men make about the future show this. It may appear to me that I shall be Chief Justice next year. But instead of that, I find myself, perhaps, in prison. In general, what appears to each individual to be the truth about the future frequently does not turn out so in the event.

(2) Perception yields contradictory impressions. The same object appears large when near, small when removed to a distance. Compared with some things it is light, with others heavy. In one light it is white, in another green, and in the dark it has no colour at all. Looked at from one angle this piece of paper seems square, from another it appears to be a rhombus. Which of all these impressions is true? To know which is true, we must be able to exercise a choice among these varying impressions, to prefer one to another, to discriminate, to accept this and reject that. But if knowledge is perception, then we have no right to give one perception preference over another. For all perceptions are knowledge. All are true.

(3) This doctrine renders all teaching, all discussion, proof, or disproof, impossible. Since all perceptions are equally true, the child's perceptions must be just as much the truth as those of his teachers. His teachers, {179} therefore, can teach him nothing. As to discussion and proof, the very fact that two people dispute about anything implies that they believe in the existence of an objective truth. Their impressions, if they contradict each other, cannot both be true. For if so, there is nothing to dispute about. Thus all proof and refutation are rendered futile by the theory of Protagoras.

(4) If perception is truth, man is the measure of all things, in his character as a percipient being. But since animals are also percipient beings, the lowest brute must be, equally with man, the measure of all things.

(5) The theory of Protagoras contradicts itself. For Protagoras admits that what appears to me true is true. If, therefore, it appears to me true that the doctrine of Protagoras is false, Protagoras himself must admit that it is false.

(6) It destroys the objectivity of truth, and renders the distinction between truth and falsehood wholly meaningless. The same thing is true and false at the same time, true for you and false for me. Hence it makes no difference at all whether we say that a proposition is true, or whether we say that it is false. Both statements mean the same thing, that is to say, neither of them means anything. To say that whatever I perceive is true for me merely gives a new name to my perception, but does not add any value to it.

(7) In all perception there are elements which are not contributed by the senses. Suppose I say, "This piece of paper is white." This, we might think, is a pure judgment of perception. Nothing is stated except what I perceive by means of my senses. But on consideration it turns out that this is not correct. First of all I must {180} think "this piece of paper." Why do I call it paper? My doing so means that I have classified it. I have mentally compared it with other pieces of paper, and decided that it is of a class with them. My thought, then, involves comparison and classification. The object is a compound sensation of whiteness, squareness, etc. I can only recognise it as a piece of paper by identifying these sensations, which I have now, with sensations received from other similar objects in the past. And not only must I recognize the sameness of the sensations, but I must recognize their difference from other sensations. I must not confound the sensations I receive from paper with those which I receive from a piece of wood. Both identities and differences of sensations must be known before I can say "this piece of paper." The same is true when I go on to say that it "is white." This is only possible by classifying it with other white objects, and differentiating it from objects of other colours. But the senses themselves cannot perform these acts of comparison and contrast. Each sensation is, so to speak, an isolated dot. It cannot go beyond itself to compare itself with others. This operation must be performed by my mind, which acts as a co-ordinating central authority, receiving the isolated sensations, combining, comparing, and contrasting them. This is particularly noticeable in cases where we compare sensations of one sense with those of another. Feeling a ball with my fingers, I say it feels round. Looking at it with my eyes, I say it looks round. But the feel is quite a different sensation from the look. Yet I use the same word, "round," to describe both. And this shows that I have identified the two sensations. This {181} cannot be done by the senses themselves. For my eyes cannot feel, and my fingers cannot see. It must be the mind itself, standing above the senses, which performs the identification. Thus the ideas of identity and difference are not yielded to me by my senses. The intellect itself introduces them into things. Yet they are involved in all knowledge, for they are involved even in the simplest acts of knowledge, such as the proposition, "This is white." Knowledge, therefore, cannot consist simply of sense-impressions, as Protagoras thought, for even the simplest propositions contain more than sensation.

If knowledge is not the same as perception, neither is it, on the other hand, the same as opinion. That knowledge is opinion is the second false theory that Plato seeks to refute. Wrong opinion is clearly not knowledge. But even right opinion cannot be called knowledge. If I say, without any grounds for the statement, that there will be a thunderstorm next Easter Sunday, it may chance that my statement turns out to be correct. But it cannot be said that, in making this blind guess, I had any knowledge, although, as it turned out, I had right opinion. Right opinion may also be grounded, not on mere guess-work, but on something which, though better, is still not true understanding. We often feel intuitively, or instinctively, that something is true, though we cannot give any definite grounds for our belief. The belief may be quite correct, but it is not, according to Plato, knowledge. It is only right opinion. To possess knowledge, one must not only know that a thing is so, but why it is so. One must know the reasons. Knowledge must be full and complete understanding, rational comprehension, and not mere instinctive belief. {182} It must be grounded on reason, and not on faith. Right opinion may be produced by persuasion and sophistry, by the arts of the orator and rhetorician. Knowledge can only be produced by reason. Right opinion may equally be removed by the false arts of rhetoric, and is therefore unstable and uncertain. But true knowledge cannot be thus shaken. He who truly knows and understands cannot be robbed of his knowledge by the glamour of words. Opinion, lastly, may be true or false. Knowledge can only be true.

These false theories being refuted, we can now pass to the positive side of the theory of knowledge. If knowledge is neither perception nor opinion, what is it? Plato adopts, without alteration, the Socratic doctrine that all knowledge is knowledge through concepts. This, as I explained in the lecture on Socrates, gets rid of the objectionable results of the Sophistic identification of knowledge with perception. A concept, being the same thing as a definition, is something fixed and permanent, not liable to mutation according to the subjective impressions of the individual. It gives us objective truth. This also agrees with Plato's view of opinion. Knowledge is not opinion, founded on instinct or intuition. Knowledge is founded on reason. This is the same as saying that it is founded upon concepts, since reason is the faculty of concepts.

But if Plato, in answering the question, "What is knowledge?" follows implicitly the teaching of Socrates, he yet builds upon this teaching a new and wholly un-Socratic metaphysic of his own. The Socratic theory of knowledge he now converts into a theory of the nature of reality. This is the subject-matter of Dialectic.

{183}

3. Dialectic, or the Theory of Ideas.

The concept had been for Socrates merely a rule of thought. Definitions, like guide-rails, keep thought upon the straight path; we compare any act with the definition of virtue in order to ascertain whether it is virtuous. But what was for Socrates merely regulative of thought, Plato now transforms into a metaphysical substance. His theory of Ideas is the theory of the objectivity of concepts. That the concept is not merely an idea in the mind, but something which has a reality of its own, outside and independent of the mind--this is the essence of the philosophy of Plato.

How did Plato arrive at this doctrine? It is founded upon the view that truth means the correspondence of one's ideas with the facts of existence. If I see a lake of water, and if there really is such a lake, then my idea is true. But if there is no lake, then my idea is false. It is an hallucination. Truth, according to this view, means that the thought in my mind is a copy of something outside my mind. Falsehood consists in having an idea which is not a copy of anything which really exists. Knowledge, of course, means knowledge of the truth. And when I say that a thought in my mind is knowledge, I must therefore mean that this thought is a copy of something that exists. But we have already seen that knowledge is the knowledge of concepts. And if a concept is true knowledge, it can only be true in virtue of the fact that it corresponds to an objective reality. There must, therefore, be general ideas or concepts, outside my mind. It were a contradiction to suppose, on the one hand, that the concept is true knowledge, and on the other, that it corresponds to nothing external {184} to us. This would be like saying that my idea of the lake of water is a true idea, but that no such lake really exists. The concept in my mind must be a copy of the concept outside it.

Now if knowledge by concepts is true, our experiences through sensation must be false. Our senses make us aware of many individual horses. Our intellect gives us the concept of the horse in general. If the latter is the sole truth, the former must be false. And this can only mean that the objects of sensation have no true reality. What has reality is the concept; what has no reality is the individual thing which is perceived by the senses. This and that particular horse have no true being. Reality belongs only to the idea of the horse in general.

Let us approach this theory from a somewhat different direction. Suppose I ask you the question, "What is beauty?" You point to a rose, and say, "Here is beauty." And you say the same of a woman's face, a piece of woodland scenery, and a clear moonlight night. But I answer that this is not what I want to know. I did not ask what things are beautiful, but what is beauty. I did not ask for many things, but for one thing, namely, beauty. If beauty is a rose, it cannot be moonlight, because a rose and moonlight are quite different things. By beauty we mean, not many things, but one. This is proved by the fact that we use only one word for it. And what I want to know is what this one beauty is, which is distinct from all beautiful objects. Perhaps you will say that there is no such thing as beauty apart from beautiful objects, and that, though we use one word, yet this is only a manner of {185} speech, and that there are in reality many beauties, each residing in a beautiful object. In that case, I observe that, though the many beauties are all different, yet, since you use the one word to describe them all, you evidently think that they are similar to each other. How do you know that they are similar? Your eyes cannot inform you of this similarity, because it involves comparison, and we have already seen that comparison is an act of the mind, and not of the senses. You must therefore have an idea of beauty in your mind, with which you compare the various beautiful objects and so recognise them as all resembling your idea of beauty, and therefore as resembling each other. So that there is at any rate an idea of one beauty in your mind. Either this idea corresponds to something outside you, or it does not. In the latter case, your idea of beauty is a mere invention, a figment of your own brain. If so, then, in judging external objects by your subjective idea, and in making it the standard of whether they are beautiful or not, you are back again at the position of the Sophists. You are making yourself and the fancies of your individual brain the standard of external truth. Therefore, the only alternative is to believe that there is not only an idea of beauty in your mind, but that there is such a thing as the one beauty itself, of which your idea is a copy. This beauty exists outside the mind, and it is something distinct from all beautiful objects.

What has been said of beauty may equally be said of justice, or of goodness, or of whiteness, or of heaviness. There are many just acts, but only one justice, since we use one word for it. This justice must be a real thing, distinct from all particular just acts. Our ideas of justice {186} are copies of it. So also there are many white objects, but also the one whiteness.

Of the above examples, several are very exalted moral ideas, such as beauty, justice, and goodness. But the case of whiteness will serve to show that the theory attributes reality not only to exalted ideas, but to others also. In fact, we might quite well substitute evil for goodness, and all the same arguments would apply. Or we might take a corporeal object such as the horse, and ask what "horse" means. It does not mean the many individual horses, for since one word is used it must mean one thing, which is related to individual horses, just as whiteness is related to individual white things. It means the universal horse, the idea of the horse in general, and this, just as much as goodness or beauty, must be something objectively real.

Now beauty, justice, goodness, whiteness, the horse in general, are all concepts. The idea of beauty is formed by including what is common to all beautiful objects, and excluding those points in which they differ. And this, as we have seen, is just what is meant by a concept. Plato's theory, therefore, is that concepts are objective realities. And he gives to these objective concepts the technical name Ideas. This is his answer to the chief question of philosophy, namely, what, amid all the appearances and unrealities of things, is that absolute and ultimate reality, from which all else is to be explained? It consists, for Plato, in Ideas.

Let us see next what the characteristics of the Ideas are. In the first place, they are substances. Substance is a technical term in philosophy, but its philosophical meaning is merely a more consistent development of its {187} popular meaning. In common talk, we generally apply the word substance to material things such as iron, brass, wood, or water. And we say that these substances possess qualities. For example, hardness and shininess are qualities of the substance iron. The qualities cannot exist apart from the substances. They do not exist on their own account, but are dependent on the substance. The shininess cannot exist by itself. There must be a shiny something. But, according to popular ideas, though the qualities are not independent of the substance, the substance is independent of the qualities. The qualities derive their reality from the substance. But the substance has reality in itself. The philosophical use of the term substance is simply a more consistent application of this idea. Substance means, for the philosopher, that which has its whole being in itself, whose reality does not flow into it from anything else, but which is the source of its own reality. It is self-caused, and self-determined. It is the ground of other things, but itself has no ground except itself. For example, if we believe the popular Christian idea that God created the world, but is Himself an ultimate and uncreated being, then, since the world depends for its existence upon God, but God's existence depends only upon Himself, God is a substance and the world is not. In this sense the word is correctly used in the Creed where it speaks of God as "three persons, but one substance." Again, if, with the Idealists, we think that mind is a self-existent reality, and that matter owes its existence to mind, then in that case matter is not substance, but mind is. In this technical sense the Ideas are substances. They are absolute and ultimate realities. {188} Their whole being is in themselves. They depend on nothing, but all things depend on them. They are the first principles of the universe.

Secondly, the Ideas are universal. An Idea is not any particular thing. The Idea of the horse is not this or that horse. It is the general concept of all horses. It is the universal horse. For this reason the Ideas are, in modern times, often called "universals."

Thirdly, the Ideas are not things, but thoughts. There is no such thing as the horse-in-general. If there were, we should be able to find it somewhere, and it would then be a particular thing instead of a universal. But in saying that the Ideas are thoughts, there are two mistakes to be carefully avoided. The first is to suppose that they are the thoughts of a person, that they are your thoughts or my thoughts. The second is to suppose that they are thoughts in the mind of God. Both these views are wrong. It would be absurd to suppose that our thoughts can be the cause of the universe. Our concepts are indeed copies of the Ideas, but to confuse them with the Ideas themselves is, for Plato, as absurd as to confuse our idea of a mountain with the mountain itself. Nor are they the thoughts of God. They are indeed sometimes spoken of as the "Ideas in the divine mind." But this is only a figurative expression. We can, if we like, talk of the sum of all the Ideas as constituting the "divine mind." But this means nothing in particular, and is only a poetical phrase. Both these mistakes are due to the fact that we find it difficult to conceive of thoughts without a thinker. This, however, is just what Plato meant. They are not subjective ideas, that is, the ideas in a particular and existent {189} mind. They are objective Ideas, thoughts which have reality on their own account, independently of any mind.

Fourthly, each Idea is a unity. It is the one amid the many. The Idea of man is one, although individual men are many. There cannot be more than one Idea for each class of objects. If there were several Ideas of justice, we should have to seek for the common element among them, and this common element would itself constitute the one Idea of justice.

Fifthly, the Ideas are immutable and imperishable. A concept is the same as a definition. And the whole point in a definition is that it should always be the same. The object of a definition is to compare individual things with it, and to see whether they agree with it or not. But if the definition of a triangle differed from day to day, it would be useless, since we could never say whether any particular figure were a triangle or not, just as the standard yard in the Tower of London would be useless if it changed in length, and were twice as long to-day as it was yesterday. A definition is thus something absolutely permanent, and a definition is only the expression in words of the nature of an Idea. Consequently the Ideas cannot change. The many beautiful objects arise and pass away, but the one Beauty neither begins nor ends. It is eternal, unchangeable, and imperishable. The many beautiful things are but the fleeting expressions of the one eternal beauty. The definition of man would remain the same, even if all men were destroyed. The Idea of man is eternal, and remains untouched by the birth, old age, decay, and death, of individual men.

Sixthly, the Ideas are the Essences of all things. The definition gives us what is essential to a thing. If we {190} define man as a rational animal, this means that reason is of the essence of man. The fact that this man has a turned-up nose, and that man red hair, are accidental facts, not essential to their humanity. We do not include them in the definition of man.

Seventhly, each Idea is, in its own kind, an absolute perfection, and its perfection is the same as its reality. The perfect man is the one universal type-man, that is, the Idea of man, and all individual men deviate more or less from this perfect type. In so far as they fall short of it, they are imperfect and unreal.

Eighthly, the Ideas are outside space and time. That they are outside space is obvious. If they were in space, they would have to be in some particular place. We ought to be able to find them somewhere. A telescope or microscope might reveal them. And this would mean that they are individual and particular things, and not universals at all. They are also outside time. For they are unchangeable and eternal; and this does not mean that they are the same at all times. If that were so, their immutability would be a matter of experience, and not of reason. We should, so to speak, have to look at them from time to time to see that they had not really changed. But their immutability is not a matter of experience, but is known to thought. It is not merely that they are always the same in time, but that time is irrelevant to them. They are timeless. In the "Timaeus" eternity is distinguished from infinite time. The latter is described as a mere copy of eternity.

Ninthly, the Ideas are rational, that is to say, they are apprehended through reason. The finding of the common element in the manifold is the work of inductive {191} reason, and through this alone is knowledge of the Ideas possible. This should be noted by those persons who imagine that Plato was some sort of benevolent mystic. The imperishable One, the absolute reality, is apprehended, not by intuition, or in any kind of mystic ecstasy, but only by rational cognition and laborious thought.

Lastly, towards the end of his life, Plato identified the Ideas with the Pythagorean numbers. We know this from Aristotle, but it is not mentioned in the dialogues of Plato himself. It appears to have been a theory adopted in old age, and set forth in the lectures which Aristotle attended. It is a retrograde step, and tends to degrade the great and lucid idealism of Plato into a mathematical mysticism. In this, as in other respects, the influence of the Pythagoreans upon Plato was harmful.

It results from this whole theory of Ideas that there are two sources of human experience, sense-perception and reason. Sense-perception has for its object the world of sense; reason has for its object the Ideas. The world of sense has all the opposite characteristics to the Ideas. The Ideas are absolute reality, absolute Being. Objects of sense are absolute unreality, not-being, except in so far as the Ideas are in them. Whatever reality they have they owe to the Ideas. There is in Plato's system a principle of absolute not-being which we shall consider when we come to deal with his Physics. Objects of sense participate both in the Ideas and in this not-being. They are, therefore, half way between Being and not-being. They are half real. Ideas, again, are universal; things of sense are always particular and individual. The Idea is one, the sense-object is always {192} a multiplicity. Ideas are outside space and time, things of sense are both temporal and spatial. The Idea is eternal and immutable; sense-objects are changeable and in perpetual flux.

As regards the last point, Plato adopts the view of Heracleitus that there is an absolute Becoming, and he identifies it with the world of sense, which contains nothing stable and permanent, but is a constant flow. The Idea always is, and never becomes; the thing of sense always becomes, and never is. It is for this reason that, in the opinion of Plato, no knowledge of the world of sense is possible, for one can have no knowledge of that which changes from moment to moment. Knowledge is only possible if its subject stands fixed before the mind, is permanent and changeless. The only knowledge, then, is knowledge of the Ideas.

This may seem, at first sight, a very singular doctrine. That there can be no knowledge of sense-objects would, it might seem to us moderns, involve the denial that modern physical science, with all its exactitude and accumulated knowledge, is knowledge at all. And surely, though all earthly things arise and pass away, many of them last long enough to admit of knowledge. Surely the mountains are sufficiently permanent to allow us to know something of them. They have relative, though not absolute, permanence. This criticism is partly justified. Plato did underestimate the value of physical knowledge. But for the most part, the criticism is a misunderstanding. By the world of sense Plato means bare sensation with no rational element in it. Now physical science has not such crude sensation for its object. Its objects are rationalized sensations. {193} If, in Plato's manner, we think only of pure sensation, then it is true that it is nothing but a constant flux without stability; and knowledge of it is impossible. The mountains are comparatively permanent. But our sensation of the mountains is perpetually changing. Every change of light, every cloud that passes over the sun, changes the colours and the shades. Every time we move from one situation to another, the mountain appears a different shape. The permanence of the mountain itself is due to the fact that all these varying sensations are identified as sensations of one and the same object. The idea of identity is involved here, and it is, as it were, a thread upon which these fleeting sensations are strung. But the idea of identity cannot be obtained from the senses. It is introduced into things by reason. Hence knowledge of this permanent mountain is only possible through the exercise of reason. In Plato's language, all we can know of the mountain is the Ideas in which it participates. To revert to a previous example, even the knowledge "this paper is white" involves the activity of intellect, and is impossible through sensation alone. Bare sensation is a flow, of which no knowledge is possible.

Aristotle observes that Plato's theory of Ideas has three sources, the teachings of the Eleatics, of Heracleitus, and of Socrates. From Heracleitus, Plato took the notion of a sphere of Becoming, and it appears in his system as the world of sense. From the Eleatics he took the idea of a sphere of absolute Being. From Socrates he took the doctrine of concepts, and proceeded to identify the Eleatic Being with the Socratic concepts. This gives him his theory of Ideas.

{194}

Sense objects, so far as they are knowable, that is so far as they are more than bare sensations, are so only because the Idea resides in them. And this yields the clue to Plato's teaching regarding the relation of sense objects to the Ideas. The Ideas are, in the first place the cause, that is to say, the ground (not the mechanical cause) of sense-objects. The Ideas are the absolute reality by which individual things must be explained. The being of things flows into them from the Ideas. They are "copies," "imitations," of the Ideas. In so far as they resemble the Idea, they are real; in so far as they differ from it, they are unreal. In general, sense objects are, in Plato's opinion, only very dim, poor and imperfect copies of the Ideas. They are mere shadows, and half-realities. Another expression frequently used by Plato to express this relationship is that of "participation." Things participate in the Ideas. White objects participate in the one whiteness, beautiful objects, in the one beauty. In this way beauty itself is the cause or explanation of beautiful objects, and so of all other Ideas. The Ideas are thus both transcendent and immanent; immanent in so far as they reside in the things of sense, transcendent inasmuch as they have a reality of their own apart from the objects of sense which participate in them. The Idea of man would still be real even if all men were destroyed, and it was real before any man existed, if there ever was such a time. For the Ideas, being timeless, cannot be real now and not then.

Of what kinds of things are there Ideas? That there are moral Ideas, such as Justice, Goodness, and Beauty, Ideas of corporeal things, such as horse, man, tree, star, river, and Ideas of qualities, such as whiteness, heaviness, {195} sweetness, we have already seen. But there are Ideas not only of natural corporeal objects, but likewise of manufactured articles; there are Ideas of beds, tables, clothes. And there are Ideas not only of exalted moral entities, such as Beauty and Justice. There are also the Ideal Ugliness, and the Ideal Injustice. There are even Ideas of the positively nauseating, such as hair, filth, and dirt. This is asserted in the "Parmenides." In that dialogue Plato's teaching is put into the mouth of Parmenides. He questions the young Socrates whether there are Ideas of hair, filth, and dirt. Socrates denies that there can be Ideas of such base things. But Parmenides corrects him, and tells him that, when he has attained the highest philosophy, he will no longer despise such things. Moreover, these Ideas of base things are just as much perfection in their kind as Beauty and Goodness are in theirs. In general, the principle is that there must be an Idea wherever a concept can be formed; that is, wherever there is a class of many things called by one name.

We saw, in treating of the Eleatics, that for them the absolute Being contained no not-being, and the absolute One no multiplicity. And it was just because they denied all not-being and multiplicity of the absolute reality that they were unable to explain the world of existence, and were forced to deny it altogether. The same problem arises for Plato. Is Being absolutely excludent of not-being? Is the Absolute an abstract One, utterly exclusive of the many? Is his philosophy a pure monism? Is it a pluralism? Or is it a combination of the two? These questions are discussed in the "Sophist" and the "Parmenides."

{196}

Plato investigates the relations of the One and the many, Being and not-being, quite in the abstract. He decides the principles involved, and leaves it to the reader to apply them to the theory of Ideas. Whether the Absolute is one or many, Being or not-being, can be decided independently of any particular theory of the nature of the Absolute, and therefore independently of Plato's own theory, which was that the Absolute consists of Ideas. Plato does not accept the Eleatic abstraction. The One cannot be simply one, for every unity must necessarily be a multiplicity. The many and the One are correlative ideas which involve each other. Neither is thinkable without the other. A One which is not many is as absurd an abstraction as a whole which has no parts. For the One can only be defined as that which is not many, and the many can only be defined as the not-one. The One is unthinkable except as standing out against a background of the many. The idea of the One therefore involves the idea of the many, and cannot be thought without it. Moreover, an abstract One is unthinkable and unknowable, because all thought and knowledge consist in applying predicates to subjects, and all predication involves the duality of its subject.

Consider the simplest affirmation that can be made about the One, namely, "The One is." Here we have two things, "the One," and "is," that is to say, being. The proposition means that the One is Being. Hence the One is two. Firstly, it is itself, "One." Secondly, it is "Being," and the proposition affirms that these two things are one. Similarly with any other predicate we apply to the One. Whatever we say of it involves its duality. Thus we find that all systems of thought which {197} postulate an abstract unity as ultimate reality, such as Eleaticism, Hinduism, and the system of Spinoza, attempt to avoid the difficulty by saying nothing positive about the One. They apply to it only negative predicates, which tell us not what it is, but what it is not. Thus the Hindus speak of Brahman as formless, immutable, imperishable, unmoved, uncreated. But this, of course, is a futile expedient. In the first place, even a negative predicate involves the duality of the subject. And, in the second place, a negative predicate is always, by implication, a positive one. You cannot have a negative without a positive. To deny one thing is to affirm its opposite. To deny motion of the One, by calling it the unmoved, is to affirm rest of it. Thus a One which is not also a many is unthinkable. Similarly, the idea of the many is inconceivable without the idea of the One. For the many is many ones. Hence the One and the many cannot be separated in the Eleatic manner. Every unity must be a unity of the many. And every many is ipso facto a unity, since we think the many in one idea, and, if we did not, we should not even know that it is a many. The Absolute must therefore be neither an abstract One, nor an abstract many. It must be a many in one.

Similarly, Being cannot totally exclude not-being. They are, just as much as the One and the many, correlatives, which mutually involve each other. The being of anything is the not-being of its opposite. The being of light is the not-being of darkness. All being, therefore, has not-being in it.

Let us apply these principles to the theory of Ideas. The absolute reality, the world of Ideas, is many, since {198} there are many Ideas, but it is one, because the Ideas are not isolated units, but members of a single organized system. There is, in fact, a hierarchy of Ideas. Just as the one Idea presides over many individual things of which it is the common element, so one higher Idea presides over many lower Ideas, and is the common element in them. And over this higher Idea, together with many others, a still higher Idea will rule. For example, the Ideas of whiteness, redness, blueness, are all subsumed under the one Idea of colour. The Ideas of sweetness and bitterness come under the one Idea of taste. But the Ideas of colour and taste themselves stand under the still higher Idea of quality. In this way, the Ideas form, as it were, a pyramid, and to this pyramid there must be an apex. There must be one highest Idea, which is supreme over all the others. This Idea will be the one final and absolutely real Being which is the ultimate ground, of itself, of the other Ideas, and of the entire universe. This Idea is, Plato tells us, the Idea of the Good. We have seen that the world of Ideas is many, and we now see that it is one. For it is one single system culminating in one supreme Idea, which is the highest expression of its unity. Moreover, each separate Idea is, in the same way, a many in one. It is one in regard to itself. That is to say, if we ignore its relations to other Ideas, it is, in itself, single. But as it has also many relations to other Ideas, it is, in this way, a multiplicity.

Every Idea is likewise a Being which contains not-being. For each Idea combines with some Ideas and not with others. Thus the Idea of corporeal body combines both with the Idea of rest and that of motion. {199} But the Ideas of rest and motion will not combine with each other. The Idea of rest, therefore, is Being in regard to itself, not-being in regard to the Idea of motion, for the being of rest is the not-being of motion. All Ideas are Being in regard to themselves, and not-being in regard to all those other Ideas with which they do not combine.

In this way there arises a science of Ideas which is called dialectic. This word is sometimes used as identical with the phrase, "theory of Ideas." But it is also used, in a narrower sense, to mean the science which has to do with the knowledge of which Ideas will combine and which not. Dialectic is the correct joining and disjoining of Ideas. It is the knowledge of the relations of all the Ideas to each other.

The attainment of this knowledge is, in Plato's opinion, the chief problem of philosophy. To know all the Ideas, each in itself and in its relations to other Ideas, is the supreme task. This involves two steps. The first is the formation of concepts. Its object is to know each Idea separately, and its procedure is by inductive reason to find the common element in which the many individual objects participate. The second step consists in the knowledge of the inter-relation of Ideas, and involves the two processes of classification and division. Classification and division both have for their object to arrange the lower Ideas under the proper higher Ideas, but they do this in opposite ways. One may begin with the lower Ideas, such as redness, whiteness, etc., and range them under their higher Idea, that of colour. This is classification. Or one may begin with the higher Idea, colour, and divide it into the lower Ideas, red, white, {200} etc. Classification proceeds from below upwards. Division proceeds from above downwards. Most of the examples of division which Plato gives are divisions by dichotomy. We may either divide colour straight away into red, blue, white, etc.; or we may divide each class into two sub-classes. Thus colour will be divided into red and not-red, not-red into white and not-white, not-white into blue and not-blue, and so on. This latter process is division by dichotomy, and Plato prefers it because, though it is tedious, it is very exhaustive and systematic.

Plato's actual performance of the supreme task of dialectic, the classification and arrangement of all Ideas, is not great. He has made no attempt to complete it. All he has done is to give us numerous examples. And this is, in reality, all that can be expected, for the number of Ideas is obviously infinite, and therefore the task of arranging them cannot be completed. There is, however, one important defect in the dialectic, which Plato ought certainly to have remedied. The supreme Idea, he tells us, is the Good. This, as being the ultimate reality, is the ground of all other Ideas. Plato ought therefore to have derived all other Ideas from it, but this he has not done. He merely asserts, in a more or less dogmatic way, that the Idea of the Good is the highest, but does nothing to connect it with the other Ideas. It is easy to see, however, why he made this assertion. It is, in fact, a necessary logical outcome of his system. For every Idea is perfection in its kind. All the Ideas have perfection in common. And just as the one beauty is the Idea which presides over all beautiful things, so the one perfection must be the supreme Idea which presides {201} over all the perfect Ideas. The supreme Idea, therefore, must be perfection itself, that is to say, the Idea of the Good. On the other hand it might, with equal force, be argued that since all the Ideas are substances, therefore the highest Idea is the Idea of substance. All that can be said is that Plato has left these matters in obscurity, and has merely asserted that the highest Idea is the Good.

Consideration of the Idea of the Good leads us naturally to enquire how far Plato's system is teleological in character. A little consideration will show that it is out and out teleological. We can see this both by studying the many lower Ideas, and the one supreme Idea. Each Idea is perfection of its kind. And each Idea is the ground of the existence of the individual objects which come under it. Thus the explanation of white objects is the perfect whiteness, of beautiful objects the perfect beauty. Or we may take as our example the Idea of the State which Plato describes in the "Republic." The ordinary view is that Plato was describing a State which was the invention of his own fancy, and is therefore to be regarded as entirely unreal. This is completely to misunderstand Plato. So far was he from thinking the ideal State unreal, that he regarded it, on the contrary, as the only real State. All existent States, such as the Athenian or the Spartan, are unreal in so far as they differ from the ideal State. And moreover, this one reality, the ideal State, is the ground of the existence of all actual States. They owe their existence to its reality. Their existence can only be explained by it. Now since the ideal State is not yet reached in fact, but is the perfect State towards which all actual States tend, it is clear that we have here {202} a teleological principle. The real explanation of the State is not to be found in its beginnings in history, in an original contract, or in biological necessities, but in its end, the final or perfect State. Or, if we prefer to put it so; the true beginning is the end. The end must be in the beginning, potentially and ideally, otherwise it could never begin: It is the same with all other things. Man is explained by the ideal man, the perfect man; white things by the perfect whiteness, and so on. Everything is explained by its end, and not by its beginning. Things are not explained by mechanical causes, but by reasons.

And the teleology of Plato culminates in the Idea of the Good. That Idea is the final explanation of all other Ideas, and of the entire universe. And to place the final ground of all things in perfection itself means that the universe arises out of that perfect end towards which all things move.

Another matter which requires elucidation here is the place which the conception of God holds in Plato's system. He frequently uses the word God both in the singular and the plural, and seems to slip with remarkable ease from the monotheistic to the polytheistic manner of speaking. In addition to the many gods, we have frequent reference to the one supreme Creator, controller, and ruler of the world, who is further conceived as a Being providentially watching over the lives of men. But in what relation does this supreme God stand to the Ideas, and especially to the Idea of the Good? If God is separate from the highest Idea, then, as Zeller points out, [Footnote 13] only three relations are possible, all of which are {203} equally objectionable. Firstly, God may be the cause or ground of the Idea of the Good. But this destroys the substantiality of the Idea, and indeed, destroys Plato's whole system. The very essence of his philosophy is that the Idea is the ultimate reality, which is self-existent, and owes its being to nothing else. But this theory makes it a mere creature of God, dependent on Him for its existence. Secondly, God may owe His being to the Idea. The Idea may be the ground of God's existence as it is the ground of all else in the universe. But this theory does violence to the idea of God, turning Him into a mere derivative existence, and, in fact, into an appearance. Thirdly, God and the Idea may be co-ordinate in the system as equally primordial independent ultimate realities. But this means that Plato has given two mutually inconsistent accounts of the ultimate reality, or, if not, that his system is a hopeless dualism. As none of these theories can be maintained, it must be supposed that God is identical with the Idea of the Good, and we find certain expressions in the "Philebus" which seem clearly to assert this. But in that case God is not a personal God at all, since the Idea is not a person. The word God, if used in this way, is merely a figurative term for the Idea. And this is the most probable theory, if we reflect that there is in fact no room for a personal God in a system which places all reality in the Idea, and that to introduce such a conception threatens to break up the whole system. Plato probably found it useful to take the popular conceptions about the personality of God or the gods and use them, in mythical fashion, to express his Ideas. Those parts of Plato which speak of God, and the governance of God, {204} are to be interpreted on the same principles as the other Platonic myths.

Before closing our discussion of dialectic, it may be well to consider what place it occupies in the life of man, and what importance is attached to it. Here Plato's answer is emphatic. Dialectic is the crown of knowledge, and knowledge is the crown of life. All other spiritual activities have value only in so far as they lead up to the knowledge of the Idea. All other subjects of intellectual study are merely preparatory to the study of philosophy. The special sciences have no value in themselves, but they have value inasmuch as their definitions and classifications form a preparation for the knowledge of Ideas. Mathematics is important because it is a stepping-stone from the world of sense to the Ideas. Its objects, namely, numbers and geometrical figures, resemble the Ideas in so far as they are immutable, and they resemble sense-objects in so far as they are in space or time. In the educational curriculum of Plato, philosophy comes last. Not everyone may study it. And none may study it till he has been through all the preparatory stages of education, which form a rigorous discipline of the mind before it finally enters upon dialectic. Thus all knowledge ends in dialectic, and that life has not attained its end which falls short of philosophy.

Perhaps the most striking illustration of the subordination of all spiritual activities to philosophy is to be found in the doctrine of Eros, or Love. The phrase "platonic love" is on the lips of many, but, as a rule, something very different from Plato's own doctrine is meant. According to him, love is always concerned with beauty, and his teaching on the subject is expounded {205} chiefly in the "Symposium," He believed that before birth the soul dwelt disembodied in the pure contemplation of the world of Ideas. Sinking down into a body, becoming immersed in the world of sense, it forgets the Ideas. The sight of a beautiful object reminds it of that one Idea of beauty of which the object is a copy. This accounts for the mystic rapture, the emotion, the joy, with which we greet the sight of the beautiful. Since Plato had expressly declared that there are Ideas of the ugly as well as of the beautiful, that there are Ideas, for example, of hair, filth, and dirt, and since these Ideas are just as divine and perfect as the Idea of the beautiful, we ought, on this theory, to greet the ugly, the filthy, and the nauseating, with a ravishment of joy similar to that which we experience in the presence of beauty. Why this is not the case Plato omitted to explain. However, having learned to love the one beautiful object, the soul passes on to the love of others. Then it perceives that it is the same beauty which reveals itself in all these. It passes from the love of beautiful forms to the love of beautiful souls, and from that to the love of beautiful sciences. It ceases to be attached to the many objects, as such, that is to say, to the sensuous envelopes of the Idea of beauty. Love passes into the knowledge of the Idea of beauty itself, and from this to the knowledge of the world of Ideas in general. It passes in fact into philosophy.

In this development there are two points which we cannot fail to note. In the first place, emotional love is explained as being simply the blind groping of reason towards the Idea. It is reason which has not yet recognized itself as such. It appears, therefore, in the {206} guise of feeling. Secondly, the later progress of the soul's love is simply the gradual recognition of itself by reason. When the soul perceives that the beauty in all objects is the same, that it is the common element amid the many, this is nothing but the process of inductive reasoning. And this development ends at last in the complete rational cognition of the world of Ideas, in a word, philosophy. Love is but an instinctive reason. The animal has no feeling of the beautiful, just because it has no reason. Love of the beautiful is founded upon the nature of man, not as a percipient or feeling being, but as a rational being. And it must end in the complete recognition of reason by itself, not in the feeling and intuition, but in the rational comprehension, of the Idea.

One can imagine what Plato's answer would be to the sort of vulgarians and philistines who want to know what the use of philosophy is, and in what way it is "practical." To answer such a question is for Plato impossible, because the question itself is illegitimate. For a thing to have a use involves that it is a means towards an end. Fire has use, because it may be made a means towards the cooking of food. Money is useful, because it is a means to the acquisition of goods. That which is an end in itself, and not a means towards any further end, cannot possibly have any use. To suggest that philosophy ought to have use is, therefore, to put the cart before the horse, to invert the whole scale of values. It suggests that philosophy is a means towards some further end, instead of being the absolute end to which all other things are means. Philosophy is not for anything. Everything else is for it. And, if this seems an exaggerated or unpractical view, we may at least {207} remember that this is the view taken by the religious consciousness of man. Religion makes the supreme end of life the knowledge of, and communion with, God. God is for religion what the Idea is for philosophy. God is a figurative name for the Idea. To place the end of life in the knowledge of the Absolute, or the Idea, is therefore the teaching both of philosophy and religion.

4. Physics, or the Theory of Existence.

Dialectic is the theory of reality, physics the theory of existence, dialectic of that which lies behind things as their ground, physics of the things which are thus grounded. That is to say, physics is concerned with phenomena and appearances, things which exist in space and time, as opposed to the timeless and non-spatial Ideas. Things of this kind are both corporeal and incorporeal. Physics falls therefore into two parts, the doctrine of the outward corporeality, the world, with its incorporeal essence, the World-Soul, and the doctrine of the incorporeal soul of man.

(a) The Doctrine of the World.

If, in the dialectic, Plato has given an account of the nature of the first principle and ground of all things, the problem now arises of explaining how the actual universe of things arises out of that ground, how it is derived from the first principle. In other words, the Ideas being the absolute reality, how does the world of sense, and, in general, the existent universe, arise out of the Ideas? Faced with this problem, the system of Plato broke down. The things of sense are, we are told, "copies" or "imitations" of the Ideas. {208} They "participate" in the Ideas. So far, so good. But why should there be any copies of the Ideas? Why should the Ideas give rise to copies of themselves, and how is the production of these copies effected? To these questions Plato has no answer, and he therefore has recourse to the use of myths. Poetic description here takes the place of scientific explanation.

This poetic description of the origin of the world is to be found in the "Timaeus." We have seen that the Ideas are absolute Being, and that things of sense are half real and half unreal. They are partly real because they participate in Being. They are partly unreal because they participate in not-being. There must be, therefore, a principle of absolute not-being. This, in Plato's opinion, is matter. Things of sense are copies of the Ideas fashioned out of, or stamped upon, matter. But Plato does not understand by matter what we, in modern times, understand by it. Matter, in our sense, is always some particular kind of matter. It is brass, or wood, or iron, or stone. It is matter which has determinate character and quality. But the possession of specific character means that it is matter with the copy of Ideas already stamped upon it. Since iron exists in great quantities in the world, and there is a common element in all the various pieces of iron, by virtue of which all are classed together, there must be a concept of iron. There is, therefore, an Idea of iron in the world of Ideas. And the iron which we find in the earth must be matter which is already formed into a copy of this Idea. It participates in the Idea of iron. The same remarks apply to any other particular kind of matter. In fact, all form, all the specific characters and {209} features of matter, as we know it, are due to the operation of the Ideas. Hence matter as it is in itself, before the image of the Ideas is stamped upon it, must be absolutely without quality, featureless, formless. But to be absolutely without any quality is to be simply nothing at all. This matter is, therefore, as Plato says, absolute not-being. Zeller conjectures, probably rightly, that what Plato meant was simply empty space. [Footnote 14] Empty space is an existent not-being, and it is totally indeterminate and formless. It accords with this view that Plato adopted the Pythagorean tenet that the differential qualities of material substances are due to their smallest particles being regular geometrical figures limited out of the unlimited, that is, out of space. Thus earth is composed of cubes. That is to say, empty space when bound into cubes (the limiting of the unlimited) becomes earth. The smallest particles of fire are tetrahedra, of air octahedra, of water icosahedra.

We have, then, on the one hand, the world of Ideas, on the other, matter, an absolutely formless, chaotic, mass. By impressing the images of the Ideas upon this mass, "things" arise, that is to say, the specific objects of sense. They thus participate both in Being and in not-being. But how is this mixing of Being and not-being brought about? How do the Ideas come to have their images stamped upon matter? It is at this point that we enter upon the region of myth. Up to this point Plato is certainly to be taken literally. He of course believed in the reality of the world of Ideas, and he no doubt also believed in his principle of matter. And he thought that the objects of sense are to be {210} explained as copies of the Ideas impressed upon matter. But now, with the problem how this copying is brought about, Plato leaves the method of scientific explanation behind. If the Ideas are the absolute ground of all things, then the copying process must be done by the Ideas themselves. They must themselves be made the principles for the production of things. But this is, for Plato, impossible. For production involves change. If the Ideas produce things out of themselves, the Ideas must in the process undergo change. But Plato has declared them to be absolutely unchangeable, and to be thus immutable is to be sterile. Hence the Ideas have within themselves no principle for the production of things, and the scientific explanation of things by this means becomes impossible. Hence there is nothing for it but to have recourse to myth. Plato can only imagine that things are produced by a world-former, or designer, who, like a human artist, fashions the plastic matter into images of the Ideas.

God, the Creator, the world-designer, finds beside him, on the one hand, the Ideas, on the other, formless matter. First, he creates the World-Soul. This is incorporeal, but occupies space. He spreads it out like a huge net in empty space. He bisects it, and bends the two halves into an inner and an outer circle, these circles being destined to become the spheres of the planets and the stars respectively. He takes matter and binds it into the four elements, and these elements he builds into the empty framework of the World-Soul. When this is done, the creation of the universe is complete. The rest of the "Timaeus" is occupied with the details of Plato's ideas of astronomy and physical {211} science. These are mostly worthless and tedious, and we need not pursue them here. But we may mention that Plato, of course, regarded the earth as the centre of the world. The stars, which are divine beings, revolve around it. They necessarily move in circles, because the circle is the perfect figure. The stars, being divine, are governed solely by reason, and their movement must therefore be circular, because a circular motion is the motion of reason.

The above account of the origin of the world is merely myth, and Plato knows that it is myth. What he apparently did believe in, however, was the existence of the World-Soul, and a few words upon this subject are necessary. The soul, in Plato's system, is the mediator between the world of Ideas and the world of sense. Like the former, it is incorporeal and immortal. Like the latter, it occupies space. Plato thought that there must be a soul in the world to account for the rational behaviour of things, and to explain motion. The reason which governs and directs the world dwells in the World-Soul. And the World-Soul is the cause of motion in the outer universe, just as the human soul is the cause of the motions of the human body. The cosmos is a living being.

(b) The Doctrine of the Human Soul.

The human soul is similar in kind to the World-Soul. It is the cause of the body's movements, and in it the human reason dwells. It has affinities both with the world of Ideas and the world of sense. It is divided into two parts, of which one part is again subdivided into two. The highest part is reason, which is {212} that part of the soul which apprehends the Ideas. It is simple and indivisible. Now all destruction of things means the sundering of their parts. But the rational part of the soul, being simple, has no parts. Therefore it is indestructible and immortal. The irrational part of the soul is mortal, and is subdivided into a noble and an ignoble half. To the noble half belong courage, love of honour, and in general the nobler emotions. To the ignoble portion belong the sensuous appetites. The noble half has a certain affinity with reason, in that it has an instinct for what is noble and great. Nevertheless, this is mere instinct, and is not rational. The seat of reason is the head, of the noble half of the lower soul, the breast, of the ignoble half, the lower part of the body. Man alone possesses the three parts of the soul. Animals possess the two lower parts, plants only the appetitive soul. What distinguishes man from the lower orders of creation is thus that he alone possesses reason.

Plato connects the doctrine of the immortality of the rational soul with the theory of Ideas by means of the doctrines of recollection and transmigration. According to the former doctrine, all knowledge is recollection of what was experienced by the soul in its disembodied state before birth. It must carefully be noted, however, that the word knowledge is here used in the special and restricted sense of Plato. Not everything that we should call knowledge is recollection. The sensuous element in my perception that this paper is white is not recollection, since, as being merely sensuous, it is not, in Plato's opinion, to be called knowledge. Here, as elsewhere, he confines the term {213} to rational knowledge, that is to say, knowledge of the Ideas, though it is doubtful whether he is wholly consistent with himself in the matter, especially in regard to mathematical knowledge. It must also be noted that this doctrine has nothing in common with the Oriental doctrine of the memory of our past lives upon the earth. An example of this is found in the Buddhist Jàtakas, where the Buddha relates from memory many things that happened to him in the body in his previous births. Plato's doctrine is quite different. It refers only to recollection of the experiences of the soul in its disembodied state in the world of Ideas.

The reasons assigned by Plato for believing in this doctrine may be reduced to two. Firstly, knowledge of the Ideas cannot be derived from the senses, because the Idea is never pure in its sensuous manifestation, but always mixed. The one beauty, for example, is only found in experience mixed with the ugly. The second reason is more striking. And, if the doctrine of recollection is itself fantastic, this, the chief reason upon which Plato bases it, is interesting and important. He pointed out that mathematical knowledge seems to be innate in the mind. It is neither imparted to us by instruction, nor is it gained from experience. Plato, in fact, came within an ace of discovering what, in modern times, is called the distinction between necessary and contingent knowledge, a distinction which was made by Kant the basis of most far-reaching developments in philosophy. The character of necessity attaches to rational knowledge, but not to sensuous. To explain this distinction, we may take as our example of rational knowledge such a proposition as that two {214} and two make four. This does not mean merely that, as a matter of fact, every two objects and every other two objects, with which we have tried the experiment, make four. It is not merely a fact, it is a necessity. It is not merely that two and two do make four, but that they must make four. It is inconceivable that they should not. We have not got to go and see whether, in each new case, they do so. We know beforehand that they will, because they must. It is quite otherwise with such a proposition as, "gold is yellow." There is no necessity about it. It is merely a fact. For all anybody can see to the contrary it might just as well be blue. There is nothing inconceivable about its being blue, as there is about two and two making five. Of course, that gold is yellow is no doubt a mechanical necessity, that is, it is determined by causes, and in that sense could not be otherwise. But it is not a logical necessity. It is not a logical contradiction to imagine blue gold, as it would be to imagine two and two making five. Any other proposition in mathematics possesses the same necessity. That the angles at the base of an isosceles triangle are equal is a necessary proposition. It could not be otherwise without contradiction. Its opposite is unthinkable. But that Socrates is standing is not a necessary truth. He might just as well be sitting.

Since a mathematical proposition is necessarily true, its truth is known without verification by experience. Having proved the proposition about the isosceles triangle, we do not go about measuring the angles of triangular objects to make sure there is no exception. We know it without any experience at all. And if we {215} were sufficiently clever, we might even evolve mathematical knowledge out of the resources of our own minds, without its being told us by any teacher. That Caesar was stabbed by Brutus is a fact which no amount of cleverness could ever reveal to me. This information I can only get by being told it. But that the base angles of an isosceles triangle are equal I could discover by merely thinking about it. The proposition about Brutus is not a necessary proposition. It might be otherwise. And therefore I must be told whether it is true or not. But the proposition about the isosceles triangle is necessary, and therefore I can see that it must be true without being told.

Now Plato did not clearly make this distinction between necessary and non-necessary knowledge. But what he did perceive was that mathematical knowledge can be known without either experience or instruction. Kant afterwards gave a less fantastic explanation of these facts. But Plato concluded that such knowledge must be already present in the mind at birth. It must be recollected from a previous existence. It might be answered that, though this kind of knowledge is not gained from the experience of the senses, it may be gained from teaching. It may be imparted by another mind. We have to teach children mathematics, which we should not have to do if it were already in their minds. But Plato's answer is that when the teacher explains a geometrical theorem to the child, directly the child understands what is meant, he assents. He sees it for himself. But if the teacher explains that Lisbon is on the Tagus, the child cannot see that this is true for himself. He must either believe the word {216} of the teacher, or he must go and see. In this case, therefore, the knowledge is really imparted from one mind to another. The teacher transfers to the child knowledge which the child does not possess. But the mathematical theorem is already present in the child's mind, and the process of teaching merely consists in making him see what he already potentially knows. He has only to look into his own mind to find it. This is what we mean by saying that the child sees it for himself.

In the "Meno" Plato attempts to give an experimental proof of the doctrine of recollection. Socrates is represented as talking to a slave-boy, who admittedly has no education in mathematics, and barely knows what a square is. By dint of skilful questioning Socrates elicits from the boy's mind a theorem about the properties of the square. The point of the argument is that Socrates tells him nothing at all. He imparts no information. He only asks questions. The boy's knowledge of the theorem, therefore, is not due to the teaching of Socrates, nor is it due to experience. It can only be recollection. But if knowledge is recollection, it may be asked, why is it that we do not remember at once? Why is the tedious process of education in mathematics necessary? Because the soul, descending from the world of Ideas into the body, has its knowledge dulled and almost blotted out by its immersion in the sensuous. It has forgotten, or it has only the dimmest and faintest recollection. It has to be reminded, and it takes a great effort to bring the half-lost ideas back to the mind. This process of being reminded is education.

With this, of course, is connected the doctrine of {217} transmigration, which Plato took, no doubt, from the Pythagoreans. Most of the details of Plato's doctrine of transmigration are mere myth. Plato does not mean them seriously, as is shown by the fact that he gives quite different and inconsistent accounts of these details in different dialogues. What, in all probability, he did believe, however, may be summarized as follows. The soul is pre-existent as well as immortal. Its natural home is the world of Ideas, where at first it existed, without a body, in the pure and blissful contemplation of Ideas. But because it has affinities with the world of sense, it sinks down into a body. After death, if a man has lived a good life, and especially if he has cultivated the knowledge of Ideas, philosophy, the soul returns to its blissful abode in the world of Ideas, till, after a long period it again returns to earth in a body. Those who do evil suffer after death severe penalties, and are then reincarnated in the body of some being lower than themselves. A man may become a woman. Men may even, if their lives have been utterly sensual, pass into the bodies of animals.

5. Ethics

(a) The Ethics of the Individual

Just as Plato's theory of knowledge begins with a negative portion, designed to refute false theories of what truth is, so does his theory of morals begin with a negative portion, intended to refute false theories of what virtue is. These two negative departments of Plato's philosophy correspond in every way. As he was then engaged in showing that knowledge is not perception, as Protagoras thought, so he now urges that {218} virtue is not the same as pleasure. And as knowledge is not mere right opinion, neither is virtue mere right action. The propositions that knowledge is perception, and that virtue is pleasure, are indeed only the same principle applied to different spheres of thought. For the Sophists whatever appeared true to the individual was true for that individual. This is the same as saying that knowledge is perception. For the Sophists, again, whatever appeared right to the individual was right for that individual. This is the same as saying that it is right for each man to do whatever he pleases. Virtue is defined as the pleasure of the individual. This consequence of the Sophistic principles was drawn both by many of the Sophists themselves, and later by the Cyrenaics.

As these two propositions are thus in fact only one principle, what Plato has said in refutation of the former provides also his refutation of the latter. The theory that virtue is pleasure has the same destructive influence upon morals as the theory that knowledge is perception had upon truth. We may thus shortly summarize Plato's arguments.

(1) As the Sophistic theory of truth destroys the objectivity of truth, so the doctrine that virtue is the pleasure of the individual destroys the objectivity of the good. Nothing is good in itself. Things are only good for me or for you. There results an absolute moral relativity, in which the idea of an objective standard of goodness totally disappears.

(2) This theory destroys the distinction between good and evil. Since the good is whatever the individual pleases, and since the pleasure of one individual is the {219} displeasure of another, the same thing is both good and evil at the same time, good for one person and evil for another. Good and evil are therefore not distinct. They are the same.

(3) Pleasure is the satisfaction of our desires. Desires are merely feelings. This theory, therefore, founds morality upon feeling. But an objective morality cannot be founded upon what is peculiar to individuals. If the moral code is to be a law binding upon all men, it can only be founded upon that which is common to all men, the universal reason.

(4) The end of moral activity must fall within, and not outside, the moral act itself. Morality must have an intrinsic, not a merely extrinsic, value. We must not do right for the sake of something else. We must do right because it is right, and thus make virtue an end in itself. But the Sophistic theory places the end of morality outside morality. We are to do right, not for its own sake, but for the sake of pleasure. Morality is thus not an end in itself, but merely a means towards a further end.

Virtue, therefore, is not pleasure, any more than knowledge is perception. Likewise, just as knowledge is not right opinion, so virtue is not right action. Right opinion may be held upon wrong grounds, and right action may be performed on wrong grounds. For true virtue we must not only know what is right, but why it is right. True virtue is thus right action proceeding from a rational comprehension of true values. Hence there arises in Plato's philosophy a distinction between philosophic virtue and customary virtue. Philosophic virtue is founded upon reason, and understands the {220} principle on which it acts. It is, in fact, action governed by principles. Customary virtue is right action proceeding from any other grounds, such as custom, habit, tradition, good impulses, benevolent feelings, instinctive goodness. Men do right merely because other people do it, because it is customary, and they do it without understanding the reasons for it. This is the virtue of the ordinary honest citizen, the "respectable" person. It is the virtue of bees and ants, who act as if rationally, but without any understanding of what they are doing. And Plato observes--no doubt with an intentional spice of humour--that such people may in the next life find themselves born as bees and ants. Plato denies philosophic virtue not only to the masses of men, but even to the best statesmen and politicians of Greece.

As true virtue is virtue which knows at what it is aiming, the knowledge of the nature of the highest aim becomes the chief question of ethics. What is the end of moral activity? Now we have just seen that that end must fall within, and not outside, the moral act. The end of goodness is the good. What, then, is the good? What is the supreme good, the summum bonum?

A note of warning is necessary before we enter upon the details of this problem. Plato frequently speaks of all moral activity aiming at, and ending in, happiness. With modern phrases ringing in our ears, we might easily suppose this to mean that Plato is a utilitarian. The utilitarianism of Bentham and Mill is distinguished by the fact that it places the end of morality in happiness. Yet Plato was not a utilitarian, and would unhesitatingly have condemned the theory of Mill. He {221} would have found it identical in principle with the Sophistic doctrine that pleasure is the end of virtue. The only difference is that, whereas the Sophists identified virtue with the pleasure of the individual, Mill makes it the pleasure of the community. That act is right which leads to "the greatest happiness of the greatest number." In practice, of course, this makes a tremendous difference. But the principle is equally objectionable because, like the Sophistic theory, it founds morality upon mere feeling, instead of upon reason, and because it places the end of morality outside morality itself. Yet the formula of Mill, that the end of morals is happiness, seems the same as Plato's formula. What is the difference?

The fact is that what Mill calls happiness Plato would have called pleasure. Pleasure is the satisfaction of one's desires, whether they are noble or ignoble. Then what is happiness? It can only be defined as the general harmonious well-being of life. Only that man is happy whose soul is in the state it ought to be in, only in fact the just, the good, and the moral man. Happiness has nothing to do with pleasure. If you could conceive an absolutely just and upright man, who was yet weighed down with every possible misery and disaster, in whose life pleasure had no part, such a man would still be absolutely happy. Happiness is, therefore, in Plato, merely another name for the summum bonum. In saying that the summum bonum is happiness, Plato is not telling us anything about it. He is merely giving it a new name. And we are still left to enquire: what is the summum bonum? what is happiness?

Plato's answer, as indeed his whole ethics, is but {222} an application of the theory of Ideas. But here we can distinguish two different and, to some extent, inconsistent strains of thought, which exist side by side in Plato, and perpetually struggle for the mastery. Both views depend upon the theory of Ideas. In the first place, the Idea, in Plato's philosophy, is the sole reality. The object of sense is unreal, and merely clogs and dims the soul's vision of the Ideas. Matter is that which obstructs the free activity of the Idea. Sense-objects hide the Idea from our view. Therefore the world of sense is wholly evil. True virtue must consist in flying from the world of sense, in retiring from the affairs of the world, and even from the beauty of the senses, into the calm of philosophic contemplation. And if this were all, philosophy, the knowledge of the Ideas, would be the sole constituent of the summum bonum. But it is possible to regard sense-objects in another light. They are, after all, copies of the Ideas. They are therefore a manifestation and revelation of the ideal world. Hence Plato is compelled by this thought to allow a certain value to the world of sense, its affairs, and its beauty.

The result of this inconsistency is, at any rate, that Plato remains broad and human. He does not, on the one hand, preach a purely selfish retirement into philosophy, or a narrow ascetic ideal. He does not, on the other hand, adopt a low utilitarian view of life, allowing value only to that which is "practical." He remains true to the Greek ideal of life as a harmonious play of all the faculties, in which no one part of man is over-developed at the expense of the others.

The result is that Plato's summum bonum is not a single {223} end. It is a compound consisting of four parts. First, and chief of all, is the knowledge of the Ideas as they are in themselves, philosophy. Secondly, the contemplation of the Ideas as they reveal themselves in the world of sense, the love and appreciation of all that is beautiful, ordered, and harmonious. Thirdly, the cultivation of the special sciences and arts. And fourthly, indulgence in pure, refined, and innocent pleasures of the senses, excluding, of course, whatever is base and evil.

Plato had also a specific doctrine of virtue. As already stated, he distinguished between philosophic and customary virtue, and attached absolute value only to the former. He does not, however, deny a relative value to customary virtue, inasmuch as it is a means towards true virtue. Plato saw that man cannot rise at one bound to the pinnacles of rational virtue. He must needs pass through the preparatory stage of customary virtue. In the man in whom reason is not yet awakened, good habits and customs must be implanted, in order that, when reason comes, it may find the ground ready prepared.

Socrates had taught that virtue is one. And Plato in his earlier writings adopted this view. But later on he came to see that every faculty of man has its place and its function, and the due performance of its function is a virtue. He did not, however, surrender the unity of virtue altogether, but believed that its unity is compatible with its plurality. There are four cardinal virtues. Three of these correspond to the three parts of the soul, and the fourth is the unity of the others. The virtue of reason is wisdom, of the noble half of {224} the mortal soul courage, of the ignoble appetites, temperance or self-control, in which the passions allow themselves to be governed by reason. The fourth virtue, justice, arises from the others. Justice means proportion and harmony, and accrues to the soul when all three parts perform their functions and co-operate with each other.

Following Zeller, we may add to this account of the virtues some of Plato's views upon the details of life. And first, his opinion of women and marriage. Here Plato does not rise above the level of ordinary Greek morals. He has nothing specially original to say, but reflects the opinions of his age. Women he regards as essentially inferior to men. Moreover, the modern view of woman as the complement of man, as possessing those special virtues of womanliness, which a man lacks, is quite alien to Plato. The difference between men and women is, in his view, not one of kind but only of degree. The only specific difference between the sexes is the physical difference. Spiritually they are quite the same, except that woman is inferior. Hence Plato would not exclude women from the same education which man receives. He would educate them in exactly the same way, but this involves the imposition upon them of the same burdens. Even military duties are not outside the sphere of women.

His views of marriage flow from the same principle. Since woman is not the complement of man, she is in no special sense fitted to be his companion. Hence the ideal of spiritual companionship is absent from Plato's view of marriage, the sole object of which, in his opinion, is the propagation of children. The natural companion {225} of a man is not a woman, but another man. The ideal of friendship, therefore, takes the place of the spiritual ideal of marriage in Plato and, indeed, among the ancients generally.

Slavery is not denounced by Plato. He takes no trouble to justify it, because he thinks it so obviously right that it needs no justification. All that can be said to his credit is that he demands humane and just, though firm and unsentimental, treatment of slaves.

If in these respects Plato never transcends the Greek view of life, in one matter at least he does so. The common view of his time was that one ought to do good to one's friends and evil to one's enemies. This Plato expressly repudiates. It can never be good, he thinks, to do evil. One should rather do good to one's enemies, and so convert them into friends. To return good for evil is no less a Platonic than a Christian maxim.

(b) The State.

We pass from the ethics of individual life to the ethics of the community. Plato's "Republic" is not an attempt to paint an imaginary and unreal perfection. Its object is to found politics on the theory of Ideas by depicting the Idea of the State. This State is, therefore, not unreal, but the only real State, and its reality is the ground of the existence of all actually existent States.