Page:The Works of William Harvey (part 1 of 2).djvu/490

 through the fluid ; in the same way, as the mucus in question rendered recrudescent by corruption, liquefies and returns to the state of sanies.

So far at this time have I thought fit to produce these my own observations on this constituent of the blood, intending to speak more fully of it as well as of the other constituents cog- nizable by the senses, and admitted by Aristotle and the medical writers.

That I may not seem to wander too widely from my purpose, I would here have it understood that with Aristotle I receive the blood as a part of the living animal body, and not as it is commonly regarded in the light of mere gore. The Stagirite says : l " The blood is warm, in the sense in which we should understand warm water, did we designate that fluid by a simple name, not viewing it as heated. For heat belongs to its nature ; just as whiteness is in the nature of a white man. But when the blood becomes hot through any affection or passion, it is not then hot of itself. The same thing must be said in regard to the qualities of dryness and moistness. Wherefore, in the nature of such things they are partly hot and partly moist ; but separated, they congeal and become cold ; and such is the blood."

The blood consequently, as it is a living element of the body, is of a doubtful nature, and falls to be considered under two points of view. Materially and per se it is called nourishment ; but formally and in so far as it is endowed with heat and spirits, the immediate instruments of the vital principle, and even with vitality (anima), it is to be regarded as the familiar divinity and preserver of the body, as the generative first engendered and very principal part. And as the prolific egg contains within it the matter, instrument, and framer of the future pullet, and all physicians admit a mixture of the seminal fluids of the two sexes in the uterus during or immediately after in- tercourse as constituting the mixed cause, both material and efficient, of the foetus ; so might one with more propriety main- tain that the blood was both the matter and preserver of the body, though not the sole aliment ; because it is observed that in animals which die of hunger, and in men who perish of

1 De Part. Anim. lib. ii, cap. 3.