If it be said that these spirits reside in the primigenial moisture as in their ultimate aliment, and flow from thence through the whole body to nourish its several parts, they propound a simple impossibility, viz. that the ingenerate heat, that primigenial element of the body, nourished itself, yet serves for the nourishment of the body at large. Upon such grounds the thing nourished and the thing that nourishes would be one and the same, and itself would both nourish and be nourished; which could in no way be effected; inasmuch as it is by no means probable that the nourishment should ever be mixed with the thing nourished, for things mixed must have equal powers and mutually act on one another ; and, according to Aristotle's dictum, "where there is nutrition, there there is no mixture." But as nutrition takes place everywhere, the nutriment is one thing, and that which is nourished by it is another, and it is altogether indispensable that the one pass into the other.
But as it is thought that the spirits, and the ultimate or primigenial aliment, or something else, is contained in animals which acts in a greater degree than the blood above the forces of the elements, we are not sufficiently informed what is un- derstood by the expression, " acting above the forces of the ele- ments " neither are Aristotle's words rightly interpreted where he says, 1 " every virtue or faculty of the soul appears to par- take of another body more divine than those which are called
elements For there is in every seed a certain something
which causes it to be fruitful, viz. what is called heat, and that not fire or any faculty of the kind, but a spirit such as is con- tained in semen and frothy bodies ; and the nature inherent in that spirit is responsive in its proportions to the element of the stars. Wherefore fire engenders no animal; neither is any- thing seen to be constituted of the dense, or moist, or dry. But the heat of the sun and of animals, and not only that which is stored up in semen, but even that of any excrementitious matter, although diverse in nature, still contains a vital prin- ciple. For the rest, it is obvious from this that the heat con- tained in animals is not fire, neither does it derive its origin from fire." Now I maintain the same things of the innate heat and
1 De Gen. Anim. lib. ii, cap. 3.
