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.