organic life was supposed to be so controlled, and even inorganic matter was thought to receive impressions from the stars. Even the members of the human body were parceled out under the control of the different planets and signs of the zodiac. How far one thought human fate under the stars simply depended on how far one attributed human action to appetite and environment, rather than to reason, will and divine interference. In any case, astronomy and astrology must be reckoned with in botany, zoology, mineralogy and medicine; and became the supreme science, the one underlying the rest.
Furthermore, astrology was no easy art, but had a very complicated technique as well as an enormous scope. The pursuit of this intricate superstition must, like the disputations and carefully analyzed arguments of the scholastics, have exercised a beneficial effect upon the muscles of the human mind. It has always been a matter of some wonder to me that, even after astrology was proved to be false, its former devotees did not continue to urge the study of this outworn subject on the ground that it would provide good mental discipline.
Medieval medicine was connected with natural science, and sometimes with astrology; but there is not time to speak of it now except to say that there were several schools or university faculties of medicine, that numerous medical treatises have come down to us, and that, while in the main medicine was still controlled by the theories and authority of Galen, there seems to have been some progress. Surgery received a new impulse in Italy in the thirteenth century, though the epoch-making discoveries of Vesalius and Harvey were still far in the future.
We have seen that Aristotle was not the sole authority of medieval science; I wish now to emphasize that it did not rely solely upon authorities, no matter how numerous. We have already heard Adelard prefer reason to mere authority, but besides reason medieval students of nature recognized observation and experience as criteria of truth. Albertus Magnus, for instance, in the later books of his work on animals, often says, "I have tested this," or "My associates and I have experienced this," or "I have proved this is not so," or "But I have not experienced that." When discussing whales, he "passes over the writings of antiquity on this topic because they do not agree with experience," and gives his own personal observations instead. Often, indeed, he questions the reliability of former writers, drawing a sharp line between those who state what they themselves have seen or experienced and those who appear to repeat rumor or folk-lore. He will not accept everything that Pliny the Elder says in his "Natural History," and he is particularly chary of accepting the assertions of Solinus and Jorach, assuring his readers that
those philosophers tell many lies and I think that this is one of their lies.
In his treatise on plants, too, which has been called the chief work
