NATURAL SCIENCE IN TEE MIDDLE AGES 285 



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 argu- 

 ments 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 sub- 

 ject on the ground that it would provide good mental discipline. 



Medieval medicine was connected with natural science, and some- 

 times 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 experi- 

 enced this," or "I have proved this is not so," or " But I have not expe- 

 rienced 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 



