Volume 2 / Book 4 — CHAPTER XXXVI

ADELARD OF BATH

Place in medieval learning—Some dates in his career—Mathematical treatises—Adelard and alchemy—Importance of the Natural Questions—Occasion of writing—Arabic versus Gallic learning—“Modern discoveries”—Medieval work wrongly credited to Greek and Arab—Illustrated from the history of alchemy—Science and religion—Reason versus authority—Need of the telescope and microscope already felt—Some quaint speculative science—Warfare, science, and religion—Specimens of medieval scientific curiosity—Theory of sound—Theory of vision—Deductive reasoning from hot and cold, moist and dry—Refinement of the four elements hypothesis—Animal intelligence doubted—The earth’s shape and center of gravity—Indestructibility of matter—Also stated by Hugh of St. Victor—Roger Bacon’s continuity of universal nature—Previously stated by Adelard—Experiment and magic—Adelard and Hero of Alexandria—Attitude to the stars: De eodem et diverso—Attitude to the stars: Questiones naturales—Astrology in an anonymous work, perhaps by Athelardus—Authorities concerning spirits—Adelard’s future influence—Appendix I. The problem of dating the De eodem et diverso and Questiones naturales and of their relations to each other—Difficulty of the problem—Before what queen did Adelard play the cithara?—Circumstances under which the De eodem et diverso was written—Different situation depicted in the Natural Questions—Some apparent indications that the De eodem et diverso was written after the Natural Questions—How long had Henry I been reigning?

“Quare, si quid amplius a me audire desideras, rationem refer et recipe.”

—Questiones naturales, cap. 6.

Place in medieval learning.

While the Breton, Abelard, and the Saxon, Hugh of St. Victor, were reviewing patristic literature from somewhat new angles and were laying the foundations of scholastic method, an Englishman, Adelard of Bath,[26] was primarily interested in exploring the fields of mathematical and natural science. As Hugh came from Saxony to Paris and Abelard went forth from his native Brittany through the towns of France in quest of Christian teachers, so Adelard, leaving not only his home in England but the schools of Gaul where he had been teaching, made a much more extensive intellectual pilgrimage even to lands Mohammedan. “It is worth while,” he declares in one of his works, “to visit learned men of different nations, and to remember whatever you find is most excellent in each case. For what the schools of Gaul do not know, those beyond the Alps reveal; what you do not learn among the Latins, well-informed Greece will teach you.”[27] Adelard seems to have devoted himself especially to Arabian learning and to have made a number of translations from the Arabic, continuing at the beginning of the twelfth century that transfer of Graeco-Arabic science which we have associated with the name of Gerbert in the tenth century and which Constantinus Africanus carried on in the eleventh century. Adelard himself hints that some of his new ideas are not derived from his Arabian masters but are his own, and Haskins has well characterized him as a pioneer in the study of natural science.

Some dates in his career.

Adelard has been described as “a dim and shadowy figure in the history of European learning,”[28] and the dates of his birth and death are unknown. We possess, however, a number of his works and some may be either approximately or exactly dated. In the preface to his translation of the astronomical tables of Al-Khowarizmi he seems to give the year as 1126.[29] The Pipe Roll for 1130 informs us that Adelard received four shillings and six pence at that time from the sheriff of Wiltshire. This suggests that he was in the employ of the king’s court,[30] and his brief treatise on the astrolabe seems to be dedicated to Prince Henry Plantagenet,[31] later Henry II, and to have been written between 1142 and 1146. It was probably one of his last works and in it he mentions specifically three earlier works.[32] Two other writings, which are the best known and apparently the most original of his works, namely the Questiones naturales and De eodem et diverso, may be dated approximately from the fact that they are dedicated respectively to Richard, Bishop of Bayeux from 1107 to 1133, and to William, Bishop of Syracuse, who died in 1115 or 1116. Both works are addressed to Adelard’s nephew, who is presumably the same person in both cases, one in the form of a letter, the other of a conversation, and both justify Adelard’s studies in foreign lands. In an appendix to this chapter the question when these two treatises were written and their relations to each other will be discussed more fully.

Mathematical treatises.

The subjects of a majority of Adelard’s known works and translations are mathematical or astronomical. The most elementary is a treatise on the abacus, Regule abaci,[33] in which his chief authorities are Boethius and Gerbert and he seems as yet unacquainted with Arabic mathematics. [34] But most of the mathematical treatises extant under Adelard’s name are from the Arabic, such as his translation of Euclid’s Elements;[35] of the astronomical tables of Al-Khowarizmi—who flourished under the patronage of the caliph Al-Mamum (813-833)—“apparently as revised by Maslama at Cordova,” under the title Liber Ezich; and, if by a “Master A” Adelard is meant, of a treatise of the first half of the twelfth century on the four arts of the quadrivium and especially on astronomy, which is apparently also a work of Al-Khowarizmi.[36] Some of the introductory books on the quadrivium have been printed,[37] but “the astronomical treatise has not yet been specially studied.”[38] One therefore cannot say how far it may indulge in astrology, but we are told that Adelard translated from the Arabic another “astrological treatise, evidently of Abu Ma’ashar Dja’afar,”[39] or Albumasar. We have already mentioned in another chapter the ascription to Adelard of one Latin translation of the superstitious work of Thebit ben Corat on astrological images, and in the present chapter the treatise on the astrolabe for Henry Plantagenet.

Adelard and alchemy.

Adelard was interested in alchemy as well as astrology and magic, if the attribution to him in a thirteenth century manuscript[40] of the twelfth century version of the Mappe clavicula is correct. We have seen that the original version of that work was much older than Adelard’s time, but he perhaps made additions to it, or translated a fuller Arabic version. The occurrence of some Arabic and English words in certain chapters of the later copies are perhaps signs of his contributions. Berthelot, however, thought that few of the new items in the twelfth century version originated with Adelard and that many of the additions were taken by him, or by whoever was responsible for the later version, from Greek rather than Arabic sources.[41]

Importance of the Natural Questions.

Our attention will be devoted chiefly to the two treatises by Adelard which we have already mentioned as the most original of his works. Of these the Natural Questions are evidently much more important than the De eodem et diverso, which is largely taken up with a justification, in the style of allegorical personification made so popular by Martianus Capella and Boethius, and with much use of Plato’s Timaeus, of the seven liberal arts against the five worldly interests of wealth, power, ambition, dignities, and pleasure. The Natural Questions, although put into a dramatic dialogue form somewhat reminiscent of Plato, deal without much persiflage with a number of concrete problems of natural science to which definite answers are attempted.

Occasion of writing.

Adelard opens the Natural Questions with brief allusion to the pleasant reunion with the friends who greeted him upon his return to England in the reign of Henry I after long absence from his native land for the sake of study. After the usual inquiries had been made concerning one another’s health and that of their friends, Adelard asked about “the morals of our nation,” only to learn that “princes were violent, prelates wine-bibbers, judges mercenary, patrons inconstant, the common men flatterers, promise-makers false, friends envious, and everyone in general ambitious.” Adelard declared that he had no intention of conforming to this wretched state of affairs, and when asked what he did intend to do, since he would not practice and could not prevent such “moral depravity,” replied that he intended to ignore it, “for oblivion is the only remedy for insurmountable ills.” Accordingly that subject was dropped, and presently his nephew suggested and the others joined in urging that he disclose to them “something new from my Arabian studies.”[42] From the sordid practical world back to the pure light and ideals of science and philosophy! Such has been the frequent refrain of our authors from Vitruvius and Galen, from Firmicus and Boethius on. It is further enlarged upon by Adelard in the De eodem et diverso; it has not quite lost its force even today; and parallels to Adelard’s twelfth century lament on England’s going to the dogs may be found in after-the-war letters to The London Times of 1919.

Arabic versus Gallic learning.

The result of the request preferred by Adelard’s friends is the present treatise in the form of a dialogue with his nephew, who proposes by a succession of questions to force his uncle to justify his preference for “the opinions of the Saracens” over those of the Christian “schools of Gaul” where the nephew has pursued his studies. The nephew is described as “interested rather than expert in natural science”[43] in the Natural Questions, while a passage in the De eodem et diverso implies that his training in Gaul had been largely of the usual rhetorical and dialectical character, since Adelard says to him, “Do you keep watch whether I speak aright, observing that modest silence which is your custom amidst the wordy war of sophisms and the affected locutions of rhetoric.”[44] In the Natural Questions the nephew, as befits his now maturer years, has more to say, raising some objections and stating some theories as well as propounding his questions, but Adelard’s answers constitute the bulk of the book. Beginning with earth and plants, the questions range in an ascending scale through the lower animals to human physiology and psychology and then to the grander cosmic phenomena of sea, air, and sky.

“Modern discoveries.”

In agreeing to follow this method of question and answer Adelard explains at the start that on account of the prejudice of the present generation against any modern[45] discoveries he will attribute even his own ideas to someone else, and that, if what he says proves displeasing to less advanced students because unfamiliar, the blame for this should be attached to the Arabs and not to himself. “For I am aware what misfortunes pursue the professors of truth among the common crowd. Therefore it is the cause of the Arabs that I plead, not my own.”[46] This is a very interesting passage in more ways than one. Adelard appears as an exponent of the new scientific school, stimulated by contact with Arabian culture. He is confident that he has valuable new truth, but is less confident as to the reception which it will receive. The hostility, however, in the Latin learned world is not, as one might expect, to Mohammedan learning. The process of taking over Arabic learning has apparently already begun—as indeed we have seen from our previous chapters—and Adelard’s Christian friends are ready enough to hear what he has learned in Mohammedan lands and schools, although of course they may not accept it after they have heard it. But he fears that he “would not get a hearing at all,” if he should put forward new views as his own. Indeed, he himself shows a similar prejudice against other novelties than his own in a passage in the De eodem, where he speaks impatiently and contemptuously of “those who harass our ears with daily novelties” and of “the new Platos and Aristotles to whom each day gives birth, who with unblushing front proclaim alike things which they know and of which they know nothing, and whose supreme trust is in extreme verbosity.”[47] Adelard of course regarded his own new ideas as of more solid worth than these, but the fact remains that he was not after all the only one who was interested in promulgating novelties. Yet his justification for writing the De eodem is the silence of “the science of the moderns” compared with the fluency of the ancients, of whose famous writings he has read “not all, but the greater part.”[48] It is not necessary, of course, to regard this passage and the preceding as inconsistent, but it is well to read the one in the light of the other.

Medieval work wrongly credited to Greek and Arab.

But let us return to the passage from the Natural Questions and Adelard’s insinuation—slightly satirical no doubt, but also in part serious—that he has fathered new scientific notions of his own upon the Arabs. There is reason to think that he was not the only one to do this. Not only were superstitious and comparatively worthless treatises which were composed in the medieval period attributed to Aristotle and other famous authors, but this was also the case with works of real value. Also the number is suspiciously large of works of which the lost originals were supposedly by Greek or Arabian authors but which are extant only in later Latin “translations.”

Illustrated from the history of alchemy.

This point may be specifically illustrated for the moment from the researches of Berthelot among alchemistic manuscripts, which have demonstrated that Latin alchemy of the thirteenth century was less superstitious and more scientific than in previous periods, whether among the ancient Greeks or more recent Arabs. He found but one treatise in Arabic which contained precise and minute details about chemical substances and operations. As a rule the Arabian alchemists wrote “theoretical works full of allegories and declamation.” For a long time several works, important in the history of chemistry as well as of alchemy, were regarded as Latin translations of the Arab, Geber. But Berthelot discovered the Arabic manuscripts of the real Geber, which turned out to be of little value and largely copied from Greek authors. On the other hand, the Latin works which had gone under Geber’s name were produced in the thirteenth and fourteenth centuries by men who seem, like Adelard of Bath, to have preferred to ascribe their own ideas to the Arabs. Let us examine for a moment with Berthelot[49] the chief of these Latin treatises. It is a “a systematic work, very well arranged. Its modest method of exposition” differs greatly from “the vague and excessive promises of the real Geber.” Much of the book possesses “a truly scientific character” and “shows the state of chemical knowledge with a precision of thought and expression unknown to previous authors.” As for Adelard’s new ideas, we may not regard them as so novel as they seemed to him, nor estimate them so highly in comparison with ancient Greek science as Berthelot did medieval compared with Greek alchemy—much of Adelard’s thought may be derived by him from those ancient writings in which he claims to have read so widely—but they were probably as new to Adelard’s Latin contemporaries as they were to himself.

Science and religion.

While Adelard’s English friends displayed no bigoted opposition to the reception of Saracen science, the question of science and religion is raised in another connection in the very first of the questions concerning nature which the nephew puts to his uncle. The nephew inquires the reason for the growth of herbs from earth, asking, “To what else can you attribute this save to the marvelous effect of the marvelous divine will?” Adelard retorts that no doubt it is the Creator’s will, but that the operation is also not without a natural reason. This attitude of independent scientific investigation is characteristic of Adelard. Again in the fourth chapter when the nephew displays a tendency to ascribe all effects to God indifferently as cause, Adelard objects. He insists that he is detracting in no way from God, whom he grants to be the source of all things, but he holds that nature “is not confused and without system” and that “human science should be given a hearing upon those points which it has covered.” On the other hand he has no desire in the present treatise to overstep the bounds of natural science and enter the field of theology. When his nephew towards the close wishes him to go on and discuss the problem of God’s existence and nature, he wisely responds, “You are now broaching a question to me where it is easier to disprove what isn’t so than to demonstrate what is,”[50] and that they had better go to bed and leave this big question for another day and another treatise.[51]

Reason versus authority.

Besides preferring the learning of Arabian and other distant lands to the schools of Gaul, and favoring scientific investigation rather than unquestioning faith, Adelard also sets reason above authority. He not only complains of his generation’s inborn prejudice against new ideas, but later on, when his nephew proposes to turn his questions from the subject of plants to that of animals, enters upon a longer diatribe against scholastic reliance upon past authorities. “It is difficult for me to discuss animals with you. For I learned from my Arabian masters under the leading of reason; you, however, captivated by the appearance of authority, follow your halter. Since what else should authority be called than a halter? For just as brutes are led where one wills by a halter, so the authority of past writers leads not a few of you into danger, held and bound as you are by bestial credulity. Consequently some, usurping to themselves the name of authority, have used excessive license in writing, so that they have not hesitated to teach bestial men falsehood in place of truth. For why shouldn’t you fill rolls of parchment and write on both sides, when in this age you generally have auditors who demand no rational judgment but trust simply in the mention of an old title?”[52] Adelard adds that those who are now reckoned authorities gained credence in the first instance by following reason, asserts that authority alone is not enough to convince, and concludes with the ultimatum to his nephew: “Wherefore, if you want to hear anything more from me, give and take reason. For I’m not the sort of man that can be fed on a picture of a beefsteak.”[53]

Need of the telescope and microscope already felt.

The history of natural philosophy and science has demonstrated that the unaided human reason has not been equal to the solution of the problems of the natural universe, and that elaborate and extensive observation, experience, and measurement of the natural phenomena are essential. But exact scientific measurement was not possible with the unaided human senses and required the invention of scientific instruments. As Adelard says in De eodem et diverso, “The senses are reliable neither in respect to the greatest nor the smallest objects. Who has ever comprehended the space of the sky with the sense of sight?... Who has ever distinguished minute atoms with the eye?”[54] Notable natural questions these, showing that the need of the telescope and microscope was already felt and that the discovery must in due time follow!

Some quaint speculative science.

We must not, therefore, unduly blame Adelard for placing, like the Greek philosophers before him, somewhat excessive trust in human reason and believing that “nothing is surer than reason, nothing falser than the senses.”[55] But in consequence much of his discussion is still in the speculative stage, and uncle as well as nephew shows the influence of dialectical training. Some quaint and amusing instances may be given. Asked why men do not have horns like some other animals, Adelard at first objects to the question as trivial; but when his nephew urges the utility of horns as weapons of defence, he replies that man has reason instead of horns, and that, as a social as well as bellicose animal, man requires weapons which he can lay aside in times of peace.[56] Asked why the nose, with its impurities, is placed above the mouth, through which we eat, Adelard answers that nothing in nature is impure, and that the nose serves the head and so should be above the mouth which serves the stomach.[57] Such arguing from the fitness of things and from design was common in the Greek philosophers whom Adelard had read, and in judging his treatise we must compare it with such books as the Saturnalia of Macrobius which he cites,[58] the Natural Questions of Seneca, Plato’s Timaeus, and the Problems of Aristotle,[59] rather than with works of modern science.

Warfare, science, and religion.

It is noteworthy, however, even in these two amusing instances that the argument from design is questioned, while the question about horns Adelard perhaps inserted as a sly hit against the militarism of the feudal age. Little recked he of the horrible substitutes for horns that twentieth century warfare would work out with the aid of modern science. The medieval church has too often been wildly accused of persecuting natural scientists and it has been erroneously stated that Roger Bacon dared not reveal the secret of the mariner’s compass—which really was well known before his time—for fear of being accused of magic.[60] There is somewhat more plausibility in the theory that he concealed the invention of gunpowder from fear of the inquisition,[61] since there appears to have been a certain medieval prejudice against inhuman war inventions, which historians of artillery somewhat impatiently ascribe to “ignorance, religion, and chivalry,” and which they hold prevented the use of Greek fire in the west.[62] At any rate in Adelard’s day the Second Lateran Council attempted to prohibit the use of military engines against men on the ground that they were too murderous.[63]

Specimens of medieval scientific curiosity.

Returning to the Natural Questions, we may note that, like the Problems of Aristotle, they vary from such crude queries as might occur to any curious person without scientific training to others that imply some previous theory or knowledge. A list of some of them will illustrate the scope of the scientific curiosity of the time. When one tree is grafted upon another, why is all the fruit of the nature of the grafted portion? Why do some brutes ruminate; why are some animals without stomachs; and why do some which drink make no water? Why do men grow bald in front? Why do some animals see better in the night than in the day and why can a man standing in the dark see objects that are in the light, while a man standing in the light cannot see objects that are in the dark? Why are the fingers of the human hand of unequal length and the palm hollow? Why don’t babies walk as soon as they are born, and why are they at first nourished upon milk, and why doesn’t milk agree equally with old and young? Why do we fear dead bodies?[64] A number of questions are devoted to each of the topics, vision, hearing, and heat, while the senses of taste, smell, and touch are dismissed in a single question and answer.[65]

Theory of sound.

The discussion of sound and vision may be noted more fully. The nephew has already learned from his Boethius something similar to the wave theory of sound. He states that when the air has been formed by the mouth of the speaker and impelled by the tongue, it impresses the same form upon that which is next to it, and that this process is repeated over and over just as concentric circles are formed when a stone is thrown into water.[66] Vitruvius had given the same explanation in discussing the acoustics of a theater.[67] But when the nephew asks his uncle how the voice can penetrate an iron wall, Adelard replies that every metal body, no matter how solid, has some pores through which the air can pass.[68] Thus he appears to regard air as the only substance which can transmit or conduct sound waves. His notion that air can pass through solids reminds one a little of the milder theory of Hero of Alexandria that heat and light consist of material particles which penetrate the interstices between the atoms composing air and water.[69] But it hardly seems as if Adelard could have derived his notion from Hero, since the impermeability of metal vessels to air is a fundamental hypothesis in many of the devices of Hero’s Pneumatics.

Theory of vision.

Adelard’s theory of vision, that of extramission of “a visible spirit,” is similar to that of Plato in the Timaeus, by which he was not unlikely influenced. The visible spirit passes from the brain to the eye through “concave nerves which the Greeks call optic,” and from the eye to the object seen and back again “with marvelous celerity.”[70] It would be interesting to know certainly whether Adelard penned this passage before John of Spain translated into Latin the De differentia spiritus et animae, in which Costa ben Luca speaks of “hollow nerves” from the brain to the eye through which the spiritus passes for the purpose of vision.[71] Apparently Adelard was first, since the Natural Questions were finished at some time between 1107 and 1133, while John of Spain is said to have made his translation for Raymond who was archbishop of Toledo from 1130 to 1150. Were the manuscripts not so insistent in naming John as translator,[72] we might think that Adelard had translated the De differentia spiritus et animae. Very possibly he had come across it during his study with Arabian masters. But he shows no acquaintance with the optical researches of Al-Hazen or with the treatise on Optics ascribed to Ptolemy, which last is extant only in the twelfth century Latin translation by Eugene of Palermo, admiral of Sicily.[73] However, the fact that three other theories of vision than the one which Adelard accepts are set forth by his nephew suggests that the problem was attracting attention. Pliny’s Natural History gave no theory of vision whatever, although he listed various cases of extraordinary sight. Boethius, on the other hand, briefly adverted to the opposing theories of vision by extramission and intramission in the first chapter of his work on music. As for the marvelous celerity of the visible spirit, Augustine had enlarged upon the vast distance to the sun and back traveled by the visual ray in an instant or twinkling of an eye.[74]

Deductive reasoning from hot and cold, moist and dry.

Throughout the Natural Questions Adelard’s explanations and answers are based in large measure upon the familiar hypothesis of the four elements and of the four qualities, hot and cold, dry and moist. When asked, for instance, why all ruminating animals begin to lie down with their hind legs, he explains that their scanty animal heat is the cause of their ruminating to aid digestion, and that there is more frigidity in their posterior members, which are consequently heavier and so are bent first in reclining. The nephew thinks that here he has caught his uncle napping, and asks why is it then that in rising they lift themselves first onto their hind legs. But Adelard is not to be so easily nonplussed, and explains that after they have lain down and rested, they feel so refreshed that they lift their heavier limbs first.[75] Again, asked why persons of quick perception often have faulty memories, Adelard suggests that a moist brain is more conducive to intelligence, but a dry one to memory. Thus moist potter’s clay receives impressions more readily but also easily loses them; what is drier receives the impression with more difficulty but retains it.[76] In a third passage, Adelard explains his nephew’s weeping in his joy at seeing his uncle safely returned by the theory that his excessive delight overheated his brain and distilled moisture thence.[77]

Refinement of the four elements hypothesis.

Adelard, however, like Galen, Constantinus Africanus, Basil, and other writers before him, finds it advisable to refine the theory of the four elements. He is at pains in his answer to the nephew’s very first question to explain that what we commonly call earth is not the element earth, and that no one ever touched the pure element water, or saw the elements air and fire. Every particular object contains all four elements and we deal in daily life only with compounds. In an herb, for instance, unless there were fire, there would be no growth upward; unless there were water or air, no spreading out; and without earth, no consistency. Moreover, when Adelard is asked why some herbs are spoken of as hot by nature, although all plants have more earth than fire in their composition, he says that while earth predominates quantitatively, efficaciously they are more fiery, just as his green cloak is larger than his green emerald, but much less potent.[78] Thus comes in the theory of occult virtue to help out the inadequate and unsatisfactory hypothesis of four elements and four qualities. We shall find our subsequent authors often resorting to the same explanation.

Animal intelligence doubted.

Adelard may believe in the marvelous virtue of emeralds, to which indeed he alludes rather inadvertently, but we do not find in the Natural Questions any of the common tales concerning remarkable animal sagacity or malice. This may be mere accident or it may be due to his warning in introducing the discussion of animals to give and take reason only. However, the question is discussed whether the brutes possess souls,[79] and he states that the common people are sure that they do not, and that only philosophers assert that animals have souls. This does not mean that their souls are rational, however: either animals possess “neither intelligence nor discretion but only opinion which is founded not in the soul but in the body”; or perhaps they have “some judgment why they seek and avoid certain things,” and such discretion of sense as enables a dog to distinguish scents. If they possess such animal souls, do these perish with the body?

The earth’s shape and center of gravity.

Adelard is correctly informed as to the shape of the earth and its center of gravity. Asked how the terrestrial globe is upheld in the midst of space, he retorts that in a round space it is evident that the center and the bottom are the same.[80] This thought is reinforced by the next question, If there were a hole clear through the earth and a stone were dropped in, how far would it fall? Adelard correctly answers, Only to the center of the earth. The same question is asked of Adelard by a Greek in the De eodem et diverso, so that, in case we regard the De eodem as written before the Natural Questions, it would appear that he had not derived his conclusion in this matter from either the Greeks or the Arabs. However, we have heard Plutarch scoff at the statement that bars weighing a thousand talents would stop falling at the earth’s center, if a hole were opened up through the earth.[81]

Indestructibility of matter.

In a recent review of Sir William Ramsay’s The Life and Letters of Joseph Black, M.D., it is stated, “The nature of the experiment he (Black) made is not now known, but his tremendous comment on it was, ‘Nothing escapes!’ Have we here really the first glimmering of the great principle of the indestructibility of matter which, with the associated principle regarding energy, forms the foundation of modern chemistry and physics?”[82] To this the answer is, “No.” Adelard of Bath stated the indestructibility of matter eight centuries earlier, and apparently not as the result of any experiment. But his utterance was fuller and more explicit than that of Black. “And certainly in my judgment nothing in this world of sense ever perishes utterly, or is less today than when it was created. If any part is dissolved from one union, it does not perish but is joined to some other group.”[83]

Also stated by Hugh of St. Victor.

The indestructibility of matter is also stated by Adelard’s contemporary, Hugh of St. Victor, who remarks in the Didascalicon that of earthly things which have a beginning and an end “it has been said, ‘Nothing in the universe ever dies because no essence perishes.’ For the essences of things do not change, but the forms. And when a form is said to change, it should not be so understood that any existing thing is believed to perish utterly and lose its being, but only to undergo alteration, either perchance so that those things which were joined are separated, or those joined which had been separated....”[84] Hugh was quite certainly a younger man than Adelard, but it is not so certain that the Didascalicon was written after the Natural Questions, although it is probable. Or Hugh may have heard Adelard lecture in Gaul or learned his view concerning the indestructibility of matter indirectly. Or they both may have drawn it independently from a common source.[85]

Roger Bacon’s continuity of universal nature.

In an article entitled Roger Bacon et l’Horreur du Vide[86] Professor Pierre Duhem advanced the thesis that in place of the previous doctrine that nature abhors a vacuum Roger Bacon was the first to formulate a theory of universal continuity. This was an incorrect hypothesis, it is true, but one which Professor Duhem believed to have served the useful purpose of supplementing “the Peripatetic theory of heavy and light” until the discovery of atmospheric pressure. This theory developed in connection with certain problematical phenomena of which this “experiment” is the chief and typical case. If there be suspended in air a vessel of water having a hole in the top and several narrow apertures in the bottom, no water will fall from it as long as the superior aperture is closed. Yet water is heavier than air and according to the principles of Aristotle’s Physics should fall to the ground. Writers before Roger Bacon, according to Duhem, explain this anomaly by saying that the fall of the water would produce a vacuum and that a vacuum cannot exist in nature. But Bacon argues that a vacuum cannot be the reason why the water does not fall, because a vacuum does not exist; he then explains further that although by their particular natures water tends downwards and air upwards, by their nature as parts of the universe they tend to remain in continuity. Duhem held that Roger Bacon was the first to substitute this positive law of universal continuity for the mere negation that a vacuum cannot exist in nature.[87]

Previously stated by Adelard.

Professor Duhem supported his case by citation of Greek, Byzantine, and Arabic sources and by use of writings of fourteenth century physicists available only in manuscripts. But unfortunately for his main contention he overlooked a remarkable passage written by Adelard of Bath over a century before Roger Bacon. In the fifty-eighth chapter of the Natural Questions the nephew says, “There is still one point about the natures of waters which is unclear to me.” He then asks his uncle to explain a water jar, similar to that just described, which they had once seen at the house of an enchantress. Adelard replies in his clear, easy style, so different from the scholastic discussion in Bacon’s corresponding passages. “If it was magic, the enchantment was worked by violence of nature rather than of waters. For although four elements compose the body of this world of sense, they are so united by natural affection that, as no one of them desires to exist without another, so no place is or can be void of them. Therefore immediately one of them leaves its position, another succeeds it without interval, nor can one leave its place unless some other which is especially attached to it can succeed it.” Hence it is futile to give the water a chance to escape unless you give the air a chance to enter. Be it noted that Adelard not only thus anticipates the theory of universal continuity, but also in the last clause of the quotation approaches the doctrine of chemical affinity in the formation and disintegration of molecules. Finally, he describes what actually occurs in the experiment more accurately than Roger Bacon or the other physicists cited by Duhem. “Hence it comes about that, if in a vessel which is absolutely tight above an aperture is made below, the liquid flows out only interruptedly and with bubbling. For as much air gets in as liquid goes out, and this air, since it finds the water porous, by its own properties of tenuity and lightness makes its way to the top of the vessel and occupies what seems to be a vacuum.”

Experiment and magic.

This detailed and accurate description of exactly what takes place shows us Adelard’s powers of observation and experiment at their best, and compares favorably with two cruder examples of experimentation which he ascribes to others. He states that it was discovered experimentally which portion of the brain is devoted to the imagination and which parts to reason and memory through a case in which a man was injured in the front part of the head.[88] In the other instance some philosophers, in order to study the veins and muscles of the human body, bound a corpse in running water until all the flesh had been removed by the current.[89] But the question remains, how often did Abelard exercise his powers of accurate observation by actual experiments? Certainly one thing is noteworthy, that the best and almost sole experiment that he details is represented by him as suggested by the magic water jar of an enchantress. Thus we are once again impelled to the conclusion that experimental method owes a considerable debt to magic, and that magic owed a great deal to experimental method.

Adelard and Hero of Alexandria.

We are also reminded of the association of similar water-jars with thaumaturgy in the Pneumatics of Hero of Alexandria.[90] It will be noted that Adelard is content with a single illustration of the principle involved, while Hero kept reintroducing instances of it. And while Hero gave little more than practical directions, Adelard gives a philosophical interpretation of and scientific deduction from the experiment. But he also describes what actually occurs more accurately, admitting that some liquid will gradually flow out even when the air-hole is kept closed. Here again, as in the case of the theory of the penetration of the particles of one substance between those of another mentioned in our paragraph above on the theory of sound, it is difficult to say whether Adelard was acquainted with Hero’s works. Probably it is only chance that Hero’s Pneumatics seems to contain almost exactly the same number of theorems as Adelard’s Natural Questions has chapters.[91]

Attitude to the stars: De eodem et diverso.

It remains to consider Adelard’s attitude towards the stars, which is very similar to that of Plato’s Timaeus. We have already seen that he translated works of Arabic astrology. Such a work as the tables of Al-Khowarizmi evidently has an astrological purpose, enabling one to find the horoscope accurately. In the De eodem et diverso he calls the celestial bodies “those superior and divine animals,” and “the causes and principle of inferior natures.” One who masters the science of astronomy can comprehend not only the present state of inferior things but also the past and the future.[92] The existence of music, says Adelard in another passage, supplies philosophers with a strong argument for their belief that “the soul has descended into the body from the stars above.”[93] In the De eodem et diverso Adelard also expresses the belief that from present phenomena the mind can look ahead far into the future, and that the soul can sometimes foresee the future in dreams.[94]

Attitude to the stars: Questiones Naturales.

In the Natural Questions[95] Adelard again alludes to the stars as “those superior animals,” and when asked whether they are animated replies that he deems anyone to be without sense who contends that the stars are senseless, and that to call those bodies lifeless which produce vitality in other bodies is ridiculous. He regards “the bodies of the stars” as composed of the same four elements as this world of inferior creation, but he believes that in their composition those elements predominate which conduce most to life and reason, and that the celestial bodies are more fiery than terrestrial bodies. “But their fire is not harsh, but gentle and harmless. It therefore follows that it is obedient to and in harmony with sense and reason.” Their form, too, being “full and round,” is especially adapted to reason. Finally, if reason and foresight exist even in our dark and perturbed lower world, how much more must the stars employ intelligence in their determined and constant courses? When the nephew proceeds to inquire what food the stars eat, since they are animals, Adelard shows no surprise, but answers that as diviner creatures they use a purer sustenance than we, namely, the humidities of earth and water which, extenuated and refined by their long upward transit, neither augment the stars in weight nor dull their reason and prudence. But when the nephew asks whether the aplanon or outermost and immovable sphere of heaven should be called God or not, Adelard answers that to assert this is in one sense philosophical but in another, insane and abominable, and he then avoids further discussion by terminating the treatise.

Astrology in an anonymous work, perhaps by Athelardus.

For some reason, which I failed to discover, the catalogue of the Cotton manuscripts in the British Museum, in describing “a philosophical treatise concerning the principles of nature, the power of celestial influences on minds and morals, and other matters,”[96] states that “the author seems to be Athelardus.” The treatise is perhaps of later date than Adelard of Bath, but as it would be equally difficult to connect it with any other of our authors, we will give some account of it now. It seems to be incomplete as it stands both at the beginning and end, but the main interest in the portion preserved to us is astrological. Authorities are cited such as Hermes Trismegistus, Theodosius, Ptolemy, Apollonius of Thebes, “Albateni,” and “Abumaxar.” Discussing the number of elements our author states that medical men speak of the four parts of the inferior world, fire, air, water, earth,[97] but that astrologers make the number of the elements twelve, adding the eight parts of the superior world.[98] Later our author argues further for astrological influence as against “the narrow medical man who thinks of no effects of things except those of inferior nature merely.”[99] Our author holds that forms come from above to matter here below, and discusses the influence of the sky on the generation of humans and metals, plants and animals, and connects seven colors and seven metals with the planets.[100] He furthermore, in all probability following Albumasar in this, asserts that the course of history may be foretold by means of astrology and that different religions go with different planets.[101] The Jews are under Saturn; the Arabs, under Venus and Mars, which explains the warlike and sensual character of their religion; the Christian Roman Empire, under the Sun and Jupiter. “Ancient writers argue” and “present experience proves”[102] that the Sun stands for honesty, liberality, and victory; Jupiter, for peace, equity, and humanity. The constant enmity between the Jews and Christians, and Moslems and Christians, is explained by the fact that neither Mars nor Saturn is ever in friendly relation with Jupiter. These three religions also observe the days of the week corresponding to their planets: the Christians, Sunday; the Moslems, Friday or Venus’s day; the Jews, Saturday. Our author also explains the worships of the Egyptians and Greeks by their relation to signs of the zodiac.

Authorities on spirits.

Despite the allusion just mentioned to “the experience of to-day,” our author perhaps shows too great a tendency to cite authorities to be that Adelard of Bath who wished to give and take reason and reproved his nephew for blind trust in authority. In discussing the theme of spirits and demons[103]—a different problem, it is true, from natural questions—he thinks that “it is enough in these matters to have faith in the authority of those who, divinely illuminated, could penetrate into things divine by the purer vision of the mind.” He proceeds to cite Apuleius and Trismegistus, Hermes in The Golden Bough, “Apollonius” in The Secrets of Nature, which he wrote alone in the desert, and Aristotle who tells of a spirit of Venus who came to him in a dream and instructed him as to the sacrifice which he should perform under a certain constellation.

Adelard’s future influence.

But I would close this chapter on Adelard not with superstition from a treatise of dubious authenticity, but rather with reaffirmation of the importance in the long history of science of his brief work, the Natural Questions. Its probable effects upon Hugh of St. Victor and Roger Bacon are instances of its medieval influence to which we shall add in subsequent chapters. But most impressive is the fact that within such compact compass it considers so many problems and topics that are still of interest to modern science. For instance, its two concrete examples of the stone dropped into a hole extending through the earth’s center and of the magic water jar have been common property ever since.

APPENDIX I

THE PROBLEM OF DATING THE DE EODEM ET DIVERSO AND QUESTIONES NATURALES AND OF THEIR RELATIONS TO EACH OTHER

Difficulty of the problem.

It is a difficult matter to fix the date either of the De eodem et diverso or of the Questiones naturales, and to account satisfactorily for the various allusions to contemporary events and to Adelard’s own movements which occur in either. It is not even entirely certain which treatise was written first, as neither contains an unmistakable allusion to the other. On general grounds the De eodem et diverso would certainly seem the earlier work, but there are some reasons for thinking the contrary. It seems clear that not many years elapsed between the composition of the two works, but how many is uncertain. It is evident that the De eodem et diverso must have been written by 1116 at the latest in order to dedicate it to William, bishop of Syracuse. But the Questiones naturales apparently might have been dedicated to Richard, bishop of Bayeux, at almost any time during his pontificate from 1107 to 1133, although probably not long after 1116.

Before what queen did Adelard play the cithara?

Professor Haskins would narrow down the time during which the De eodem et diverso could have been written to the years from about 1104 to 1109, with the single year 1116 as a further possibility. He says, “Adelard speaks of having played the cithara before the queen in the course of his musical studies in France the preceding year, and as there was no queen of France between the death of Philip I and the marriage of Louis VI in 1115, the treatise, unless the bishop of Syracuse was still alive in 1116, would not be later than 1109.”[104] But may not the queen referred to have been Matilda, the wife of Henry I?[105] She was a patroness both of artists and of men of letters, and the Pipe Roll for 1130 and the treatise on the astrolabe have shown us that later, at least, it was the English royal family with which Adelard, himself an Englishman, was connected. It is of “Gaul,” not of “France” in the sense of territory subject to the French monarch, that Adelard writes,[106] and Normandy was of course under Henry’s rule after the battle of Tinchebrai in 1106.

Circumstances under which the De eodem et diverso was written.

The De eodem et diverso takes the form of a letter[107] from Adelard to his nephew, justifying his “laborious itinerary” in pursuit of learning against the reproach of “levity and inconstancy” made by the nephew, and stating “the cause of my travel among the learned men of various regions,” at which the nephew has time and again expressed his astonishment, and the reasons for which his uncle has kept concealed from him for two years.[108] This letter seems to have been written by Adelard in Sicily, since it is prefaced with a dedication to William, bishop of Syracuse, and since towards its close Adelard speaks of “coming from Salerno into Graecia maior”[109]—a phrase by which he presumably refers to the ancient Magna Graecia, or southern Italy, and perhaps also Sicily. In the preceding year, however, Adelard and his nephew had been together in Tours.[110] It thus appears that the De eodem was written not very long after Adelard set out on his quest for foreign learning, while he was still in the Greek or semi-Greek learned society of southern Italy and Sicily, and presumably before he had come into contact with the science of the Saracens, which he does not mention in the De eodem et diverso, although traces of it undoubtedly lingered in Sicily. He writes as if the idea had only comparatively recently come to him “that he could much broaden his education, if he crossed the Alps and visited other teachers than those of Gaul.”

Different situation depicted in the Natural Questions.

In the Natural Questions, on the other hand, he returns to England after seven years, instead of a single year, of separation from his nephew, after a visit to the principality of Antioch,[111] and after a considerable period of study among the Saracens or Arabs. It is rather natural, however, to conclude that the same absence abroad is referred to in both treatises, and that Adelard wrote De eodem et diverso to his nephew after he had been absent a year, while the Natural Questions was composed after his return at the end of seven years. Thus six years would separate the two treatises. But the Natural Questions depicts a different last parting of uncle and nephew from that of De eodem et diverso. It does not allude to their having been together in Tours seven years ago, but reminds the nephew how, when his uncle took leave of him and his other pupils at Laon seven years since, it was agreed between them that while Adelard investigated Arabian learning, his nephew should continue his studies in Gaul.[112] In the De eodem et diverso, on the contrary, neither Laon nor the Arabs nor any such agreement between uncle and nephew is mentioned. Rather, the uncle seems to have at first kept secret the motives for his crossing the Alps. It therefore may be that Adelard had returned from Sicily to Gaul and had taught at Laon for a short time before setting out on a longer period of travel in quest of Arabian science. This would agree well enough with his allusion to his nephew in the De eodem et diverso as “still a boy,”[113] and the statement in the Natural Questions that his nephew was “little more than a boy”[114] when he parted from him seven years before. In this case the Natural Questions would have been written more than seven years after the De eodem et diverso. This is, I think, the most tenable and plausible hypothesis.

Some apparent indications that the De eodem et diverso was written after the Natural Questions.

There are, it is true, one or two circumstances which might be taken to indicate that the De eodem et diverso was written after the Questiones naturales. In the sole manuscript of the De eodem thus far known[115] it follows that treatise, and its title Of the same and different might be taken as a continuation with variations of the general line of thought of the other treatise. But it is perhaps just because some copyist has so interpreted its title that it is put after the Natural Questions in this manuscript. At any rate in the text itself Adelard gives another explanation of its title, stating that it has reference to the allegorical figures, Philosophia and Philocosmia, who address him in his vision, and who, he says, are designated as eadem and diversa “by the prince of philosophers,”—an allusion perhaps to some of Aristotle’s pronouns.[116] Another curious circumstance is that the problem, How far would a stone of great weight fall, if dropped in a hole extending through the earth at the center? occurs in both the De eodem and Natural Questions.[117] In the latter the nephew puts the query to his uncle: in the former a Grecian philosopher whom Adelard has been questioning concerning the properties of the magnet in attracting iron, in his turn asks Adelard this question. Now in the Natural Questions Adelard’s answer is given, as if the nephew had never heard it before, but in the De eodem et diverso it is simply stated that the Greek “listened to my explanation of this,” as if the nephew had already heard the explanation from his uncle.[118]

How long had Henry I been reigning?

In opening the Natural Questions Adelard states that Henry I was reigning when he returned to England recently. This statement, in Professor Haskins’ opinion, “would seem to imply that he originally left England for his studies in France before Henry’s accession.” I am not quite sure that this inference follows, but if it does, may one not go a step further and argue that Henry I had come to the throne since Adelard parted from his nephew at Laon to investigate the learning of the Arabs? Had Henry become king of England while Adelard was still studying or teaching in northern Gaul, he would almost certainly have heard of it, and it would have been no news to him on his return from his studies among the Arabs. If we accept this view, Adelard’s return to England would be not later than 1107. But it could scarcely be earlier, if he wrote and dedicated the Natural Questions promptly after his arrival, of which he speaks as a recent event in that work, since the dedicatee did not become Bishop of Bayeux until 1107. And if the De eodem et diverso was written more than seven years before the Natural Questions, we should have to date it back into the eleventh century, which would perhaps be too early for its dedication to William, bishop of Syracuse. And to put these two works so early is to leave a gap between them and the other known dates of Adelard’s career, 1126, 1130, and 1142-1146, and make the period of his literary productivity quite a long one. He would have been quite a graybeard when he wrote on the astrolabe for the juvenile Henry Plantagenet. On the whole, therefore, I am inclined to think that Henry I had been reigning for some time when Adelard wrote the Natural Questions.