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.