XVI INTRODUCTION. 



diligence there can be no doubt. Every chapter in his treatises bears 

 testimony to it. What proportion, indeed, of the huge array of facts 

 there stored was due to his own personal observations, to his dissec-' 

 tions, vivisections, and occasional experimentations, what was borrowed 

 from others, it is impossible to say with any exactness, P'or the works 

 of his predecessors and contemporaries have perished almost completely; 

 and the laudable custom of citing the authority on which a statement 

 is made had not yet been established. As yet there was no mistrust of 



Tother observers, because as yet it was not known how easy it is for an 

 jpbserver to be misled. Aristotle does indeed occasionally mention a 

 name, but it is the name of some one whose statement he rejects, and very 

 rarely, if ever, the name of one whose statement he borrows.^ Nor 

 must it be supposed that Aristotle's generalisations, though often false, 

 were utterly puerile. Among them are not a few that, with little or no 

 modification, have stood the test of time ; and some even that, restated 

 by moderns in ignorance of his writings, have been cksmed by them- 

 selves or their admirers as deserving high credit. Tt U^law of organic 

 I e^quivale nts, for instance, the general statement, that is, that Nature 

 must save in one part if she spends in another, be it true or false, has 

 been claimed for Goethe and for Geoifroy St.-Hilaire. Yet it had 

 been stated in unmistakable ternis^over and over again in this treatise 

 of Aristotle's.* The advantage ((f^ hysiological division of labour "was 

 first set forth," says Milne-Edwards,' " by myself in 1827 ;" yet Aristotle 

 had said repeatedly that it is preferable when possible to have a separate 

 organ for a separate office ; and that Nature never, if she can help it, 

 makes one organ answer two purposes, as a cheap artist makes " spit 

 and candlestick " in one.* That the position of an organism in the 

 kingdom to which it belongs is not to be settled by a single differentia, 



(but by a consideration of its aggregate charact ers ; " that the complexity 

 of life varies with the complexity of the organisation ; ' that the struc- 

 tural differences of the alimentary organs are correlated with differences 

 of the animal's alimentation ; ^ that no animal is endowed with more 

 than one adequate means of defence against its enemies ; ^ that there 

 is an inverse relation between the development of horns and of teeth ; • 



* Thus, when A. borrows the account of the hippopotamus (H. A. ii. 7) almost verbatim 

 from Herodotus, he makes no mention of his authority ; neither does he when he takes 

 from the same source the account of a skull without sutures (H. A. iii. 7, 3) ; but on three 

 occasions, when he contradicts him, he mentions in so doing his name (H. A. iii. 22, i, 

 D. G. ii. 2, II, and iii. 5, 15). From Ctesias he takes without acknowledgment the 

 account of the parrot, and very probably of the elephant ; but whenever he mentions 

 Ctesias by name, it is to contradict him flatly. His treatment of Plato is exceptional. 

 For though he frequently, in the De Partibus, alludes to statements in the Timaeus to 

 reject them, he always forbears in so doing to mention his former teacher's name. 



* Cf. ii. 9, note 9. ^ Lemons sur la Phys. i. 16. * Cf iv. 6, note 15. 

 » D. P. i. 3, 14. 6 D. P. iv. 7, I. ' D. P. iii. 14. 



* Cf. iii. 2, note 9. ' Cf. iii. 2, note 19. 



