438 



GENERAL ZOOLOGY 



separation of theory and fact, which invariably occurs when 

 theories are not put to the test of agreement with the 

 facts. "We must not," he said, "accept a general prin- 

 ciple from logic only, but must prove its application to 

 each fact; for it is in facts that we must seek general prin- 

 ciples, and these must always accord with facts." Though 



so clearly stated, the 

 principle was forgot- 

 ten by the world until 

 it was restated by 

 Francis Bacon (1561- 



M '^^^i Ilk I 626 ) in the seven- 



J|| II teenth century. To be 



B sure, the English Fran- 



ciscan monk, Roger 



Bacon (1214-1292), 

 appreciated the neces- 



BP|M mj sity of observation in 



^r^'^-mfm nature, and himself 

 JjHl if applied the inductive 



^B ; jf I al^r method in some of his 



m dr / Ji work, but the time was 



not then ripe for a 

 general appreciation of 

 the importance of the 

 principle. 



Aristotle also owes his preeminence over other Greek 

 writers on natural history to the variety and extent of his 

 own observations, to his voluminous collection of the obser- 

 vations and statements of others, and to his theories of life, 

 which are curiously anticipatory of some features of modern 

 evolutionary views. To refer first to his own observations, 

 it has been computed from Aristotle's works that he was 

 more or less acquainted with over five hundred species of 



FIG. 230. Aristotle 



