428 ON GENERATION: 



and prepared, and a variety of other particulars all tending, not 

 without foresight, to the development of the embryo, before the 

 first rudiment or the merest particle of this is conspicuous, 

 what should hinder us from believing that the calidum innatum 

 and the vegetative soul of the chick are in existence before the 

 chick itself? For what is competent to produce the effects and 

 acts of life, except their efficient cause and principle, heat, 

 namely, and the faculty of the vegetative soul ? Therefore it 

 would seem that the soul was not the act of the organic body 

 possessing life in potentia; for we regard the chick with its 

 appropriate form as the consequence of such an act. But where 

 can we suppose the form and vital principle of the chick to inhere 

 save in the chick itself? unless indeed we admitted a separa- 

 tion of forms and conceded a certain metamorphosis. 



Now this appears most obviously where the same animal 

 lives, as Aristotle has it, by or under a succession of forms, for 

 example, a caterpillar, a chrysalis, a butterfly. For it is of 

 necessity the same efficient, nutrient, and conservative principle 

 that possesses each of these, although under different forms ; 

 unless we allow that there is one vital principle in the youth, 

 another in the man, a third in the aged individual, or maintain 

 that the forms of the grub and caterpillar are the same as those 

 of the silkworm and butterfly. Aristotle has entered very fully 

 into this subject, and we shall ourselves have more to say on 

 it immediately. 



It appears further paradoxical to maintain that the blood is 

 produced, and moves to and fro, and is imbued with vital spirits, 

 before any sanguiferous or locomotive organs are in existence. 

 Neither is it less new and unheard-of to assert, that sensation 

 and motion belong to the foetus before the brain is formed ; 

 for the foetus moves, contracting and unfolding itself, when 

 there is nothing more than a little limpid water in the place 

 of the brain. 



Moreover, the body is nourished and increases before the 

 organs appropriated to digestion, viz. the stomach and abdo- 

 minal viscera, are formed. Sanguification, too, which is en- 

 titled the second digestion, is perfect before the first, or chyli- 

 fication, which takes place in the stomach, is begun. The ex- 

 crementitious products of the first and second digestions, namely, 

 excrement in the intestines, urine and bile in the urinary and 



