The History of Biology 377 



and in so far as a knowledge of the human body was essential to prevent 

 wounded men from bleeding to death. 



Aristotle (384-322 B. C), who was the pupil of Plato, was one of 

 the first men to think of botany and zoology as definite branches of 

 study. His great contribution to Biology was the discovery of the fact 

 that nature worked by definite fixed laws — what we now call the law 

 of continuity. 



This discovery is intensely important because it made experimental 

 science possible. There would be but little use in spending months and 

 years in attempting to prove anything, if the laws of nature worked 

 differently at different times, under the same conditions ; for, the real 

 value of experimenting is found in one's ability to> prophesy that the 

 same result will always take place if the same experiment is performed 

 under the same conditions. 



The first mark of a true scientist is accurate observation and perfect 

 description, and the second is the power of visualization, by which he 

 can build up and mold his interpretations into a principle. 



Aristotle had a mind of the highest type, and so his generalizations 

 still hold good after a lapse of thousands of years, provided, always, that 

 his facts were correct. He did not have the instruments for accurate 

 observation that we now have, so he often had to take for granted many 

 things which have since been proved erroneous. But, his logic never 

 failed him when his facts were right. 



Theophrastus (370-286 B. C.) laid the foundations of botany. The 

 astounding point that meets one in the reading of these old philosophers 

 is that they were able to work out so great an amount of detail with 

 the poor equipment they had, when we, with all our modern improved 

 apparatus, must search most diligently before we can accomplish the 

 same results. 



As medical men were the first workers in Biology proper, 

 Hippocrates (460-370 B. C.) the father of medicine, must be mentioned. 

 He made medicine a separate science and set forth the ideals of the 

 medical man which are still an inspiration to all. 



Dioscorides (about 64 A. D.), an army surgeon under Nero, and 

 Galen (131-201 A. D.), physician to Marcus Aurelius and his son Corn- 

 modus, were both Greek physicians. The former originated the pharma- 

 copoeia, which was the standard textbook of botany for some fifteen, 

 centuries. The latter wrote an anatomy and physiology which also was 

 a standard textbook for medical students for the same length of time. 



Pliny the Elder (23-79 A. D.) wrote a book which, although sup- 

 posed to be accurate, had fact and fancy blended to so considerable an 

 extent that it is hard to separate them. 



The men mentioned above are the only biological workers of whom 

 we have any record up to the time Christianity began to function. 



The Roman Empire was mistress of the world at this time, and 



