It is true that both questions and answers in this pioneer book of natural science are usually more amusing than instructive to the modern reader, although Adelard in his prologue says that he is sure his treatise will be useful to his hearers, but not that it will prove entertaining (tractatum. . . quem quidem auditoribus suis utilem fore scio, iocundum nescio). Asked why men do not have horns, Adelard first objects that the question is trivial; but when the nephew urges the utility of horns as weapons of defense, Adelard replies that man has reason instead of horns, and that, as a social as well as bellicose animal, he requires arms which he can lay aside in time of peace. Asked why the nose is placed above the mouth, he replies that it serves the head while the mouth serves the stomach. Many of his explanations are grounded upon the hypothesis current since the Greek philosopher Empedocles, that all nature is composed of four elements, earth, air, fire and water, and characterized by four qualities, hot, cold, dry and moist. Thus when Adelard is asked why bright students often have poor memories, he answers that a moist brain is conducive to intelligence, and a dry cerebrum to memory. He explains his nephew's weeping for joy to see his uncle safely returned from the Orient by the theory that his excessive delight heated his brain and distilled moisture thence.
But reasoning from a general theory of nature to explain particular phenomena is not Adelard's sole method; he also relies on experience. Nor are all his notions crude and incorrect. While he accepts the long established theory of four elements, he is careful to explain that the earth which we see and call by that name is not the element earth, and that no one has ever touched the element water, or seen the elements fire and air. Every particular object contains all four elements, and in daily life we deal only with compounds.
Adelard states the eternity of matter as follows:
And certainly in my judgment nothing in this sensible world ever perishes or is less to-day than when it was created. If a part is dissolved from one union, it does not perish but is joined to some other group.
When his nephew asks him to explain the working of a magic water jar which they once saw at an enchantress's house, and which had holes in both top and bottom so that the attendant could check the flow of water from the bottom by placing his fingers over the apertures in the top, Adelard accounts for the trick by saying that nature abhors a vacuum. Asked how far a stone would fall, if it were dropped into a hole which extended through the center of the earth, he states that it would fall as far as the center and stop there.
We have heard Adelard upholding scientific argument and investigation against a narrow religious attitude. This position is further illustrated by a contemporary of his, William of Conches in Normandy. William, too, complains that the age is instinctively hostile to new
