HISTORICAL DEVELOPMENT OF ZOOLOGY 439 



animals, though he was unable to classify them except in a 

 superficial way. His lack of an exact knowledge of anatomy 

 rendered anything like a natural classification impossible. 

 He was, however, familiar with the external appearance of 

 many organs and was able to note the adaptation of organs 

 to different functions. His writings consist not only of his 

 own observations but also of statements about animals taken 

 from every source, and many of these, it must be confessed, 

 seem to us of to-day so plainly untrue and impossible of 

 belief that it is difficult for us to understand how they 

 could have been credited by the philosopher whose vision 

 extended so widely. However, Aristotle's History of Ani- 

 mals was the source, as we^shall see, from which, for many 

 centuries, much of the natural-history lore of Europe was 

 drawn. The question concerning a disputed point, then, 

 was not, What do the facts say? but, What is written in 

 Aristotle ? 



It has just been said that Aristotle held views suggestive 

 of those of modern evolutionists. Though he could not .have 

 had a sufficient basis of facts from which to draw conclu- 

 sions, he yet conceived of a complete gradation in nature, 

 beginning with the inorganic world, passing through the 

 plants to animals, and ending with man. Like others of his 

 time, Aristotle believed in the development of living from 

 non-living matter (spontaneous generation), and he pictured 

 the change as taking place directly, even with some of the 

 higher animals. With much that is false and mistaken, enough 

 of value and brilliancy remains in -the work of Aristotle to 

 entitle him to be called the founder of zoology. 



Passing mention should be made of one other Greek, 

 the philosopher and physician Galen (born A.D. 130). He 

 deserves credit for being the first to insist that medicine 

 must rest on a knowledge of anatomy and physiology. Dis- 

 section of the human body being forbidden, he examined the 



