4 1. I. 



already mentioned, and begin with the phenomena presented by- 

 each group of animals, and, when this is done, proceed afterwards 

 to state the causes of those phenomena, and to deal with their 

 evolution. For elsewhere, as for instance in house building, this 

 is the true sequence. The plan of the house, or the house, has 

 this and that features ; and because it has this and that features, 

 therefore is its construction carried out in this or that manner. 

 For the process of evolution is for the sake of the thing finally 

 evolved, and not this for the sake of the process. Empedocles, 

 then, was in error when he said that many of the characters pre- 

 sented by animals were merely the results of incidental occurrences 

 during their development ; for instance, that the backbone was 

 divided as it is into vertebrae, because it happened to be broken 

 owing to the contorted position of the foetus in the womb.^ In 

 so saying he overlooked the fact that propagation implies a creative 

 seed endowed with certain formative properties. Secondly, he 

 neglected another fact, namely, that the parent animal pre-exists, 

 not only in idea, but actually in time. For man is generated from 

 man ; and thus it is the possession of certain characters by the 

 parent that determines the development of like characters in the 

 child. The same statement^ [namely, that the process of pro- 

 duction occurs for the sake of the thing produced] holds good 

 also for the operations of art, and even for those which are appa- 

 rently spontaneous. For the same result as is commonly produced 

 only by art may sometimes occur spontaneously. Spontaneity, 

 for instance, may do the work of the physician and bring about 

 the restoration of health. As a general rule, however, the pro- 

 ducts of art are such as cannot possibly be produced spontaneously; 

 for they require the pre-existence of an efficient cause homogeneous 

 with themselves, such as the statuary's art which must necessarily 

 precede the statue ; art indeed consisting in the conception of 

 the result to be produced before its realisation in the material. 

 %\s with spontaneity,^ so with chance ; for this also occasionally 

 produces the same result as art, and by the same process of 

 evolution. 



The fittest mode, then, of treatment is to say, a man has such 

 and such parts, because the conception of a man includes their 

 presence, and because they are necessary conditions of his exist- 

 ence, or at any rate of his perfection ; and these conditions in 

 their turn imply other prior conditions. Thus we should say, 

 640 b. 



