504 ON GENERATION. 



too, when we find the brain of many animals unfurnished with 

 ventricles? And supposing it were true that any kind of air 

 or vapour was found there, seeing that all nature abhors a 

 vacuum, still it does not seem over probable that it should be 

 of heavenly origin and possessed of such superlative virtues. 

 But what we admire most of all is that a spirit, the native of 

 the skies, and endowed with such admirable qualities, should 

 be nourished by our common and elementary air ; especially 

 when we see it maintained that the elements can do nothing 

 that is beyond their natural powers. 



It is admitted, moreover, that the spirits are in a perpetual 

 state of flux, and most readily dissipated and corrupted ; nor in- 

 deed can they endure for an instant unless renovated by due 

 supplies of their appropriate nutriment, they as much require 

 incessant nourishing as the primum vivens, or first animate atom 

 of the body. What occasion is there, then, I ask, for this ex- 

 traneous inmate, for this ethereal heat ? when the blood is com- 

 petent to perform all the offices ascribed to it, and the spirits 

 cannot separate from the blood even by a hair's breadth without 

 destruction; without the blood, indeed, the spirits can neither 

 move nor penetrate anywhere as distinct and independent 

 matters. And whether they are engendered and are fed and 

 increased, as some suppose, from the thinner part of the blood, 

 or from the primigenial moisture, as others imagine, all still 

 confess that they are nowhere to be found apart from the 

 blood, but are inseparably connected with it as the aliment 

 that sustains them, even as the flame of a lamp or candle is 

 inseparably connected with the oil or tallow that feeds it. 

 The tenuity, subtilty, mobility, &c. of the spirits, therefore, 

 bring no kind of advantage more than the blood, which it 

 seems they constantly accompany, already possesses. The blood 

 consequently suffices, and is adequate to be the immediate in- 

 strument of the soul, inasmuch as it is everywhere present, 

 and moves hither and thither with the greatest rapidity. Nor 

 can it be admitted that there are any other bodies or qualities 

 of a spiritual and incorporeal nature, or any more divine kinds 

 of heat, such as light, as Caesar Cremoninus, 1 a great adept in 

 the Aristotelian philosophy, strenuously contends against 

 Albertus that there are. 



1 Dictate vii. 



