DEVELOPMENT OF ZOOLOGY 519 



in three works — "HistoHaAnimalium," "DePartibus, " and "De 

 Generatione ' '■ — what was known of the nature and classification 

 of animals, their anatomy, and their development; and (2) in 

 his own great discoveries he, more than any other of the ancients, 

 insisted on the scientific method of depending on observed facts 

 rather than on tradition. 



He did the first task so well that his successors did little 

 to follow his scientific point of view for nearly 2,000 years, 

 but merely asked what Aristotle had said on the subject. 



Another Greek, Galen, did for medicine very much what 

 Aristotle did for zoology. He made anatomy and physiology 

 the foundation of medicine. Because it was forbidden to 

 dissect the human body, he studied the bodies of monkeys 

 and other mammals. For centuries his successors, also, followed 

 his conclusions without using his methods. 



The name of the Roman, Pliny (23-79 a.d.) is usually men- 

 tioned here because of a great collection of writings on natural 

 phenomena. He fell away, however, from the spirit of Aristotle 

 and Galen, and brought together without much discrimina- 

 tion facts and nature-anecdotes of the most fanciful kind. The 

 Romans did very little for natural science. 



514. The Middle Ages. — During this remarkable period of 

 human history (400-1500 a.d.) practically no progress was 

 made in the natural sciences. It was a period of waning of 

 the old human civilizations and the incubation of the new. 

 Wars, difficulty of travel, the other-world attitude of the 

 Christian church, and many other things discouraged observa- 

 tion of nature and discovery. It was a time of mysticism, of 

 metaphysical speculation, and of large dependence on the 

 authorities. A large portion of it has been called, not inappro- 

 priately, the Dark Ages. 



515. The Modem Period (1500-1900) and its Specializations. 

 — In every department of human interest the revival following 

 the "dark ages" is one of the most remarkable movements of 

 history. This is no less true in our science than elsewhere. It 

 was more than a revival of interest. The authority of the 

 church and of the past had so intrenched itself that the greatest 

 difficulty lay in getting back freedom of investigation and 



