INTEODUCTORY. 15 



through Aristotle's writings only that ichthyology, like all 

 other branches of zoology, first took the form of a science."* 

 Eubulides and others charged x^ristotle with ingratitude 

 to Plato. This charge has been much discussed by modern 

 writers, and in connection with it it may be said that in 

 Aristotle's zoological works there are passages which, like 

 the one in his History of Animals, iii. c. 3, s. '2, about 

 the heart being the origin of the blood-vessels, look like 

 developments of statements found in Plato. Aristotle is 

 deserving of censure for not acknowledging Plato, if he was 

 indebted to him for the groundwork of such passages. To 

 decide whether this was so seems to be impossible, for, 

 independently of arguments which might be adduced for 

 settling it, the question is complicated by the fact that for 

 some years Aristotle was Plato's most gifted pupil, and the 

 imparting of ideas may not always have been from tutor to 

 pupil. In matters connected with the nature and arrange- 

 ment of the parts of animals Plato may have been some- 

 what indebted to Aristotle. 



Much labour has been spent by Aristotelian 



Aristotle's scholars in trying to determine the relative 



Works dealing positions of Aristotle's works, and a consider- 



Naturll'sdence. ^"^^^^^ ^f some of the views held on this 

 subject may be of interest. Not only is the 

 evidence on which the inquiry rests of such a nature that it 

 is difficult to estimate its true value, but the inquiry itself is 

 complicated by the probability that Aristotle had more than 

 one work on hand at one and the same time. 



It is usually considered that Aristotle's Physics, Heavens, 

 Generation and Destruction, and Meteorology, were written 

 before the zoological treatises, including the De Anima, and 

 that these were begun soon after the Meteorology . There 

 are, in fact, some apparently genuine passages in the Meteoro- 

 logy which strongly support this view. The Physics was 

 probably written before the Heavens which, it has been 

 computed from the description of an occultation of Mars in 

 Book ii. c. 12, 292«. of that work, was written after B.C. 357. 

 There is also a passage in Meteorol. iii. c. 2, s. 9, which 

 suggests that the Meteorology was not completed before 

 B.C. 334, for Aristotle there says that he had known of only 

 two instances of lunar rainbows during a period of over fifty 

 years. 



'•' Hist. Nat. des Foissons, Paris, 1828-49, vol. i. pp. 15-16. 



