34 Greek Biology 



the catamenia which are suspended during gestation for this 

 very purpose. The matter is thus summed up by Aristotle. 



' The male does not emit semen at all in some animals, and 

 where he does, this is no part of the resulting embryo ; just 

 so no material part comes from the carpenter to the material, 

 i.e. to the wood in which he works, nor does any part of the 

 carpenter's art exist within what he makes, but the shape and 

 the form are imparted from him to the material by means of 

 the motion he sets up. It is his hands that move his tools, his 

 tools that move the material ; it is his knowledge of his art, 

 and his soul, in which is the form, that move his hands or any 

 other part of him with a motion of some definite kind, a motion 

 varying with the varying nature of the object made. In like 

 manner, in the male of those animals which emit semen, Nature 

 uses the semen as a tool and as possessing motion in actuality, 

 just as tools are used in the products of any art, for in them lies 

 in a certain sense the motion of the art.' x 



4 For the same reason the development of the embryo takes 

 place in the female ; neither the male himself nor the female 

 emits semen into the female, but the female receives within 

 herself the share contributed by both, because in the female 

 is the material from which is made the resulting product. Not 

 only must the mass of material from which the embryo is in 

 the first instance formed exist there, but further material must 

 constantly be added so that the embryo may increase in size. 

 Therefore the birth must take place in the female. For the 

 carpenter must keep in close connexion with his timber and 

 the potter with his clay, and generally all workmanship and the 

 ultimate movement imparted to matter must be connected 

 with the material concerned, as, for instance, architecture is 

 in the buildings it makes.' 2 



The problem of the nature of generation is one in which 



1 De generatione animalium, i. 22 ; 730^ 10. 



2 De generations ammaHum, i. 22 ; 73o a 34. 



