PARTS OF ANIMALS, III. iv. 



other differences in the heart ; some hearts are large, 

 some small, some are hard, some soft ; and these 

 tend by some means to influence the creature's 

 temperament. Illustrations of this are : animals 

 whose powers of sensation are small have hearts that 

 are hard and dense, those Avhose sensation is keen 

 have softer ones ; and those with large hearts are 

 cowardly, those with small or moderate-sized ones, 

 courageous (this is because in the former class the 

 affection which is normally produced by fear is 

 present to begin with," as their heat is not proportion- 

 ate to the size of their heart, but is small and there- 

 fore hardly noticeable in the enormous space that it 

 occupies ; so that their blood is comparatively cold). 

 The following creatures have large hearts : the hare, 

 the deer, the mouse, the hyena, the ass, the leopard, 

 the marten, and practically all other animals whose 

 cowardice is either outright or else betrayed by their 

 mischievous behaviour. 



Similar conditions obtain in the blood-vessels and 

 the cavities of the heart : if they are large, they are 

 cold. The effect of the same-sized fire is less in a 

 large room than in a small one ; and the same applies 

 to the heat in these receptacles, the blood-vessels and 

 the cavities. Further, extraneous motions have a 

 cooling effect upon hot things ; and the more roomy 

 a receptacle is, the greater the amount of air (or 

 pneinna) in it and the stronger its effect. Thus we 

 find that no animal which has large cavities or large 

 blood-vessels has fat flesh, and conversely, that all (or 

 most) fat animals have indistinguishable blood-vessels 

 and small cavities. 



The heart is the only one of the viscera — indeed 



» Cf. 650 b 27. See also 692 a 20. 



245 



