GENERATION OF ANIMALS, V. i. 



no instance is either its existence or its formation 

 " for the sake of something." " Thus, the existence 

 and the formation of an eye is " for the sake of some- 

 thing." but its being blue is not — ^unless this con- 

 dition is a peculiarity proper to the particular class 

 of animal. And further, in some cases this condition 

 has nothing to do with the logos * of the animal's 

 being ; instead of that, we are to assume that these 

 things come to be by necessity, and so their causes 

 must be referred back to the matter and to the 

 source which initiated their movement."^ Remember 

 what was said at the beginning, at the outset of our 

 discussion.** So far as the regular, definite products 

 of Nature's hand are concerned, whatever a thing 

 may be as regards its quality, the reason why each 

 thing is of such or such a quality is not because 

 it gets formed such while it develops ; the truth is 

 that things get formed such because they are such," 

 for of course the process of formation takes its lead 

 from the being, and is for the sake of that ; the 

 being does not take its lead from the process.^ The 

 old physiologers, however, thought the opposite, 

 because they did not see that the causes were 

 numerous ; they recognized only the Material Cause 

 and the Motive Cause (and even these they did not 

 clearly distinguish), whereas they paid no attention 

 to the Formal Cause and the Final Cause?) 



Each thing, then, i* " for the sake of something," ^ 



• Cf. Dante, Paradiso xx. 78, quoted on p. 1. 



' ovaia here is no doubt, in the first place, the individual 

 existing thing which the process is destined to produce (see 

 736 b 27, n., and 767 b 34 fF.); but we may also remember 

 the use of ovaia with reference to the essential nature of a 

 thing, as in the phase Xoyos -rfjs ovaias, 1. 35 above. 



' i.e., on account of some Final Cause. 



487 



