Book 7 — NOTES ON SENECA’S “QUAESTIONES NATURALES”

By Sir Archibald Geikie, K.C.B., Pres.R.S.

The treatise of which the present volume is a translation possesses a twofold interest. In the first place, it is probably the last literary work of a man who filled a large space in the Roman world of his day. After a varied career as philosopher, barrister, politician, statesman, courtier, and man of letters, he at last incurred the implacable enmity of Nero, to whom he had been tutor. Having in his youth paid some attention to physical inquiries, he had then been led to prepare and publish a book on earthquakes. But in subsequent years the absorbing cares of State probably left him little leisure to continue these studies, for which, however, he had retained his taste. Hence, when in his last days he sought in retirement to devote himself to philosophical pursuits, he naturally turned to some of the physical problems that had interested him in earlier life. The earthquake which on 5th February A.D. had done much damage to the towns of Campania, revived his youthful enthusiasm for the investigation of such phenomena, and may possibly have suggested to him the preparation of another volume dealing with this and other scientific matter. We know at least from the book itself that he wrote a part, if not the whole, of it after that date (221, 230),‍* and that he took pains to collect information about the catastrophe. As he was in the habit of sojourning on the shores of the Bay of Naples, he probably visited the scene of destruction himself for the purpose of his book. We learn from Tacitus that it was immediately after his return from Campania to his villa near Rome, bringing with him, we may suppose, his nearly completed manuscript, that Seneca received the Emperor’s order to commit suicide.

* The numbers within parentheses throughout these Notes refer to the pages of the Translation.

In the second place, Seneca’s work on Natural Questions stands out as one of the few treatises on physical science which have come down to us from antiquity. It is interesting alike for the quotations it contains from the works of previous authors, some of which have not survived, and for the criticisms and opinions which he himself expresses on the various subjects of which he treats. It can hardly, however, be regarded as an original contribution to science. Its author’s life had been spent in other and widely different pursuits, which led him far away from scientific inquiry. But as a summary of the general state of knowledge in his day, made by a man of strong intellect, who had been trained in the legal and philosophical schools of the time, and had read widely and reflected much on these matters, the book may be taken to afford a fair presentation of the manner in which a number of questions in astronomy, meteorology, and physical geography were regarded by thoughtful minds in the first century of our era.

In judging of the intrinsic merit of such a work as the present, the modern reader finds a difficulty in realising from the broad platform of natural knowledge which, after the labours of the intervening centuries, has now been laid, how exceedingly narrow was the circle of ascertained fact available to the student two thousand years ago. The spirit of scientific observation and experiment had not then been developed, yet the familiar phenomena of everyday life pressed, as they still do, for explanation. Man’s knowledge of nature was then too limited to furnish a basis for distinguishing what was fact from what was mere guesswork. In the infancy of our race, as in the childhood of the individual, the tendency of the human mind is to perceive resemblances rather than differences. Analogies are readily observed and, in default of knowledge of the facts involved, are mistaken for identical sequences of cause and effect. Throughout the interpretations of natural phenomena given by the philosophers of antiquity, it is remarkable to what a large extent the meaning of one appearance is explained by comparing it with another to which in reality it may bear no resemblance. Seneca’s volume abounds in examples of this use of analogy.

The authority of great names exercised a wonderful fascination on the minds of the early investigators of nature. Generation after generation of writers were led to accept with little or no modification the dicta of eminent philosophers who had preceded them. An observer might sometimes recognise the erroneousness of the opinion of a predecessor, and yet lack the means of detecting the falsity of his own, which nevertheless he propounded with full assurance of its truth. In such circumstances criticism had no secure foundation, while credulity, rampant in the world outside, could hardly fail to show itself in philosophic circles. Even the most cautious and truth-seeking inquirer might easily and almost inevitably be led to accept statements which did not seem to him unreasonable, and which no previous experience of his own or others warranted him to disbelieve or even to suspect.

It behoves us, therefore, to be on our guard lest, from our much higher standard of knowledge, we may be tempted to look with amused contempt on the puerile conceptions of nature to be met with in the writings of the ancients—the grave assertion of absurdities as actual facts, the inept analogies, the confident explanations which are no explanations at all, and the complete absence of any attempt to test by examination or experiment the validity of statements which with but little trouble could have been disproved.

These evidences of the exceedingly imperfect knowledge of his time are fully illustrated in Seneca’s chapters. He quotes some two dozen of previous writers who had dealt with the same or cognate subjects. It is needless to say that they were Greeks, no place having yet been found in Latin literature for treatises on Science. The author most frequently cited by him is Aristotle, whose Meteorologica he had evidently studied with care. He gives frequent quotations from that work, but even where he does not specifically quote, his views generally accord with those of the great philosopher and naturalist.‍102 Almost the only quotations from the works of his own countrymen are verses from some of the poets, especially from Virgil and Ovid. It is remarkable that he makes only one quotation from Lucretius, although he would have found in that poet’s noble work many passages more apposite to his subject than those which he has taken from the Aeneid, the Georgics, and the Metamorphoses. We may suppose that these works were favourites with him, and that he knew much of them by heart, but that he was less familiar with the De Rerum Natura.

It is manifest from the present volume that its author, like Lucretius before him, had a lofty conception of the dignity and moral influence of the study of nature. This pursuit seemed to him to raise us above the sordid things of life and to withdraw the mind from the body—a dissociation so eminently beneficial to our higher aspirations. He believed that in the study of the hidden phenomena of the universe a mental alacrity is developed which will be found to be not without practical utility in the conduct of affairs that lie nearer the surface (113).

With this clear recognition of the importance of his theme he resolved in his old age to enter upon a task which other less worthy pursuits had hindered him from pursuing. He would now attempt to survey the universe, unravel its secrets, and give the results of his studies to the world (109). It was not, however, his aim to compose a systematic treatise on Natural Philosophy, but rather to take up some special subjects and deal with them in the light of what had already been written upon them, and of what his own reflections suggested. His undertaking assumed the form of a series of epistolary essays addressed to his friend Lucilius Junior, procurator of Sicily. The literary shape thus selected allowed the use of an unconstrained, almost colloquial, style which would not have been suitable to a more ambitious work.

Had Seneca designed to prepare a formal or methodical treatise, he would doubtless have planned it to include the three sections which he regarded as comprising every inquiry that can arise as to the nature and constitution of the Universe (Universum)—celestial, atmospheric, and terrestrial (Caelestia, Sublimia, Terrena, 51). The world (Mundus) in his view comprehends all things that come or can come within our cognisance (54). Instead of entering upon a full discussion of any one of his three sections, he selected from them a few topics which had probably more particularly engaged his attention. Most of these belong to the second or atmospheric division of his scheme of arrangement, to which he devotes six of his seven books, the remaining one being given to the discussion of some celestial phenomena. Certain subjects which we should naturally range in the terrestrial series, such as the source and flow of rivers and the nature and origin of earthquakes, he explicitly includes among his atmospheric phenomena (51).

It appears to be probable that Seneca had neither finished nor revised his manuscript at the time of his death. Parts of the work are obviously incomplete, though some of these gaps may be due to defects of transcription or to the subsequent loss of parts of the text. The obscurities of language, which are not infrequent, may likewise have partly arisen from lack of the author’s revision of his original copy. His discussion of the problem of the rise of the Nile suddenly breaks off in such an abrupt manner as to suggest the loss of a portion of the original volume. One of the most important omissions is the absence of any account of the phenomena of volcanoes. The author does indeed refer in several places to this subject, but with Aetna before him, of which so many Greek and Latin poets had sung, and which had so often been referred to in the writings of the philosophers, he could hardly have meant to offer no commentary on so notable a feature in the geography and history of his own country. We know indeed that he was keenly interested in this mountain, and that he wrote to Lucilius to ascend the volcano and send him particulars about it. In the letter conveying this request he alludes to some of the Roman poets who had sung of its wonders, and urges that a description of Aetna should form part of a poem on which his correspondent appears to have been then engaged.‍103 Another important subject in physical geography finds no place in Seneca’s volume—the Sea. Of the outer ocean it was not to be expected that he could have had much to say, but we can hardly suppose that he would have considered his essay complete without some discussion of the various phenomena presented by the Mediterranean Sea.

A century before Seneca’s prime, the immortal De Rerum Natura of Lucretius had appeared at Rome, wherein the origin and constitution of the world were sung with the intense earnestness, brilliant imagination, and resounding cadence of a great poet and with the grasp and penetration of a great philosopher. In this splendid work some of the problems discussed by Seneca were considered, and explanations were given of them with the usual undoubting confidence of olden time. In literary quality the two writers stand far apart, yet it is not uninteresting to compare their respective views of nature. The vivid and often majestic diction of the one is not more diverse from the somewhat familiar and conversational tone of the other than are their respective creeds. Lucretius was a convinced and enthusiastic Epicurean, and in accordance with the teachings of his master denied the existence of any divine co-operation in the plan and government of the Universe,

nequaquam nobis divinitus esse paratam naturam rerum,‍104

although no writer either of ancient or modern time has had a more overpowering sense of the beauty, majesty, and order of this world. It was his earnest purpose to show men how, by a contemplation of the face and ordered scheme of nature, they could free themselves from the bond of religious superstition and the fear of death.‍105

Seneca, on the other hand, held the Stoic belief in an all-wise and omnipotent Creator. In an eloquent exordium to his volume, and in a peroration near its end, he affirms his conviction that this Divine Being is all in all, at once within and without his works; He has clothed himself with creation, but is hidden from our eyes and can be perceived only by thought (3, 7, 305). Our philosopher could not conceive of anything more beautiful, more orderly, and more consistent everywhere in plan than the world around us. That such a world should have resulted from the tumult of chaos, by the mere chance collocation of atoms, appeared to him the madness of vulgar error. Yet it was only too true, though it might be thought hardly credible, that even philosophers had been tainted with this pernicious doctrine. Hence it would be in the author’s judgment a profitable task to inquire into the truth concerning these matters. To explore this world, he remarks, is far more than enough for a single lifetime. Whether what we may be led to believe regarding it shall be true must be decided by those who may attain the knowledge of the truth; we can but examine and conjecture, with no certain assurance of discovery, yet not without hope (304). It behoves us to be ever watchful against forming conclusions rashly, disrespectfully, or ignorantly, and of being knowingly untrue. In this quest after knowledge, while much may be found out which will be of practical usefulness, we are encouraged to advance, not by any hope of gain, but by the wonder with which the inquiry fills the soul. To obtain a knowledge of Nature is the highest reward to which the mind of man can aspire (230, 304). Seneca’s practical conclusion was thus much the same as that of Lucretius. He does not, however, attempt in this volume to enforce it with the solemn earnestness shown by the poet, though he loses no opportunity of inveighing against the follies and vices of his time. In discussing natural phenomena his first desire is to explain them, and in so doing to animadvert on the explanations of previous writers, with perhaps a not unnatural wish to show his own ability as a critic and expositor.

It was in due accordance with the principles of his school, as well as with his own natural temperament, that Seneca should continually be led to draw ethical lessons from the physical phenomena which he discussed. The interpolation of some of these reflections may occasionally seem to a modern reader rather irrelevant and far-fetched, but there can be no question as to the spirit of reverence with which he approached his subject. Like other philosophers who had preceded him, he maintained this spirit, while at the same time he had discarded the crowded and confused polytheism of the prevalent mythology. But he here keeps this antagonism in due restraint, only occasionally expressing his dissent from the popular creed. He would not admit that even the old philosophers could have been so foolish as to credit the gods with some of the acts which had been popularly attributed to them. He refused to believe that the guardian and ruler of the Universe hurled thunderbolts with his own hand. Still less could he suppose that the gods had lighter bolts with which they amused themselves in play. His expression (fulminibus lusoriis, 91) recalls the bitter irony of Lucretius and the sarcasm of his question whether, when the gods aim at lonely places or at the sea, they are only at practice to strengthen their arms.‍106 But Seneca held with Lucretius that in the contemplation of nature we obtain the courage and elevation of mind which fit us for the trials of life and the coming of death (113).

In the treatment of scientific problems Seneca displays the same unhesitating assurance of the truth of his opinions, which was characteristic of the philosophers of antiquity. These writers had hardly a glimmering conception of nature’s infinite complexity, of the extreme diversity and intricacy of natural processes, of the unbroken and endlessly ramifying relations of cause and effect, of the long and patient investigation by which alone these relations could be unravelled, and of the caution and diffidence with which conclusions regarding them should at least for a time be formulated. Seneca frequently passes caustic criticisms on the views expressed by his predecessors. He styles the philosophers, as a body, “a credulous folk.” Some of them he even goes so far as to accuse of perpetrating deliberate falsehoods (276, 286, 289). Nor does he hesitate to banter his brethren of the Stoic School, whose “absurdities,” as he calls them, he cannot refrain from quoting.

Yet when his own opinions are examined in the light of the present day, they are found to be in many cases no nearer the truth than those which he rejected with contempt. It is, indeed, sometimes difficult to realise the mental position of a man who could adopt and propound them. In many cases he accounts for a phenomenon by the analogy of another to which it has no real affinity, as where he explains halos by the circular undulations produced on a surface of water into which a stone is thrown (13). He sometimes suggests an experiment to prove the truth of his assertion, but if he had made the experiment he would have found how completely it failed to support him, as, for instance, when he states that a large pond of water reflects only one image of the sun, but that, if it is divided into several smaller ponds by the insertion of partitions, it will show as many images as there are divisions (18). Striking also and numerous are the examples of his credulous acceptance of statements which, had it occurred to him to test them by actual examination, he could easily have found to be erroneous. He affirms, for instance, more than once, that while lightning melts metals, it freezes wine, and he gravely alleges that when the wine is thawed and imbibed, it either kills or drives mad those who partake of it (79, 97). He asserts that the waters of certain rivers have the power of dyeing whole flocks of sheep, black fleeces being changed into white, and white into black (137), that some waters are so dense that even the heaviest objects will not sink in them (138); that the heat of the sun in the Nile valley is so great as to melt silver and the joints of statues (173). When he proceeds to explain the reason of such abnormalities he expresses no hesitation, but delivers his opinion with the assurance of a professor who has obtained the experimental demonstration in his laboratory.

It is remarkable that although some progress had been made in astronomy, especially by Greek philosophers, before the beginning of the Christian era, the conclusions arrived at by these observers regarding the relations of the earth to the other heavenly bodies met with but little acceptance for many centuries, even among reflecting minds. Lucretius, for example, still believed the earth to be the centre of the Universe to which all the heavier materials had converged, while the fire-laden ether escaped to the outer boundaries of space, sun, moon, and stars occupying an intermediate place. He did not think that the sun can be much larger than it looks to be to our senses, nor was he quite sure whether it is the same sun which, passing under the earth, reappears in the morning, or if at the close of each day the sun is extinguished and a new collection of fires makes a fresh sun in the morning. He was quite aware of the different views of Chaldaean sages and astronomers, but in such questions he could see no reason why one theory should be better than another.‍107

Seneca, however, had, on the whole, a more advanced appreciation of the relations of the earth to the heavenly bodies. He believed the sun to be larger than our globe, and that a thousand stars might be put together without equalling his mass (284, 288). He thought the heavens to be so vast as to afford space for the swiftest of the planets to rush along with uninterrupted speed during full thirty years (7). He showed his enlightened outlook upon astronomical possibilities when he surmised that comets may have orbits that carry them far beyond the Zodiac, and when he conjectured that other planets than those then known remained to be discovered (296–299). And yet, sharing these more enlarged conceptions, he clung with curious pertinacity to some of the old childish faith which was natural in the infancy of mankind. He knew that some philosophers held that it is the earth which revolves and not the heavens, and though he does not deliberately reject this opinion, it is evident that he still held that the heavens circle round the earth.‍108 Again and again he expresses his conviction that the force which sustains the energy of the sun and the stars consists of the exhalations that arise from the surface of the earth. These exhalations, he says, are the pasturage of the heavenly bodies, the breath of the world. It would be impossible, he asserts, for the earth to furnish so ample a store of nourishment to bodies larger than itself unless it were full of breath which is passing off from every part of its surface both by day and night. To the obvious objection that the supply of this energy would soon become exhausted, he has the reply that this exhaustion would certainly take place were it not that the elements are in a condition of continual transformation, issuing in one form, passing into each other, and returning to their original positions, thence to begin their cycle anew (55, 198, 244–5). In this universal transmutation water passes into air, air into water; air likewise is changed into fire, fire into air, while earth is formed from water, and water from earth (120).

In his general conception of the universe, Seneca, as a Stoic philosopher, recognised a principle of evolution. He believed that the world embraces in its constitution everything that it is destined to experience from its beginning to its end. As a human embryo contains the germ of the future man, so at the first creation of the universe, sun and moon, the changes of the stars, and the birth of living things were all embraced. And there were likewise included the forces whereby the earth is affected, and which will ultimately lead to the final destruction of the globe (151).‍109

With regard to the earth itself, whether it is to be regarded as a soul or as an organised body, Seneca announced his conviction that it has been constructed much after the plan of our human bodies. As in these bodies, veins and arteries are provided for the reception of blood and breath, so in the earth there are passages, some for the transport of water, others for the flow of air (126). He was sure, also, that everything on the surface of the earth has its counterpart beneath—caves, mountains, lakes, and rivers.