ON GENERATION. 315 



spirit had been spent, it would forthwith be useless and sterile. 

 Hence, too, physicians may learn that the semen of the male is 

 the architect of the progeny, not because the first conception 

 is embodied out of it, but because it is spiritual and effervescent, 

 as if swelling with a fertilising spirit, and a preternatural in- 

 fluence. For otherwise the story of Averrhoes, of the woman 

 who conceived in a bath, might bear an appearance of truth. 

 But of these things more in their proper place. 



In the same manner then as the egg is formed from the 

 hen, so is it probable, that from the females of other animals, 

 as will hereafter be shown, the first conceptions take both ma- 

 terial and form ; and that, too, some little time after the semen 

 of the male has been introduced, and has disappeared again. 

 For the cock does not confer any fecundity on the hen, or her 

 eggs, by the simple emission of his semen, but only in so far as 

 that fluid has a prolific quality, and is imbued with a plastic 

 power; that is to say, is spiritual, operative, and analogous to 

 the essence of the stars. The male, therefore, is no more to 

 be considered the first principle, from which conceptions and 

 the embryo arise, because he is capable of secreting and emit- 

 ting semen, than is the female, which creates an egg without 

 his assistance. But it is on this consideration rather that he 

 is entitled to his prerogative, that he introduces his semen, im- 

 bued as it is with the spirit and the virtue of a divine agent, 

 such as, in a moment of time, performs its functions, and con- 

 veys fertility. For, as we see things suddenly set on fire and 

 blasted by a spark struck from a flint, or the lightning flashing 

 from a cloud, so equally does the seed of the male instantly 

 affect the female which it has touched with a kind of contagion, 

 and transfer to her its prolific quality, by which it renders 

 fruitful in a moment, not only the eggs, but the uterus also, 

 and the hen herself. For an inflammable material is not set 

 on fire by the contact of flame more quickly, than is the hen 

 made pregnant by intercourse with the cock. But what it is 

 that is transferred from him to her, we shall afterwards find 

 occasion to speak of, when we treat this matter specially and 

 at greater length. 



In the meantime we must remark, that, if it be derived 

 from the soul, (for whatever is fruitful is probably endowed 

 also with a soul ; and we have said before, that the egg, in 



