THE SEQUOIA 



advanced the study of anatomy by his careful dissections of apes 

 and some of the lower animals, and he also wrote extensively on 

 physiology; but accurate as some of his observations were, his 

 errors, particularly in physiology, were many. His works, how- 

 ever, remained authoritative for fully 1 400 years ; his statements 

 overruled the demonstrations of nature, and he was so reverenced 

 that whoever had the courage to dispute him was liable to per- 

 secution and ostracism. 



Physiology was not materially different from metaphysics, 

 and both were affected with superstition. The ancient belief that 

 the body contained four humors — "blood," "phlegm," "yellow 

 bile," "black bile" — was held, and Galen had added to these a 

 "pneuma," which pervaded the whole body, mingling with the 

 humors and supporting life. The proper mixture of four ele- 

 ments — heat, cold, wetness and dryness — constituted the normal 

 individual. The administration of drugs was in accordance with 

 this belief. Systematic zoology did not exist. There was no true 

 conception of species, no accurate description of animals, and no 

 adequate system of classification. The naturalists were merely 

 compilers and copyists of Aristotle and other ancient writers. 



The philosophical or speculative in biology was retained by 

 the clergy, almost the only persons really interested in the conser- 

 vation of documents, and as a class the only ones able to read and 

 write. 



Some of the Greeks had had explanations of the succession of 

 organisms on the globe. Aristotle believed that the first animals 

 arose from the ocean, and that low forms of life were constantly 

 springing into existence by spontaneous generation, a fallacy 

 which was not completely rooted out of biology until the nine- 

 teenth century. Aristotle also perceived the principle of adap- 

 tation in nature, and considered the universe as the result of 

 Intelligent Design. These ideas of the Greeks had a marked 

 influence on Christian thought for many centuries. Augustine 

 (fifth century) believed that a living substance had been made 

 by the Creator, and that from this had developed all the diverse 

 organisms of the present time. Two other famous churchmen 

 advocated similar views, Erigena in the ninth century, and 



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