"The following few points should be considered well by every diligent mind, and so the fact becomes established more clearly, that those remarkable virtues which learned men attribute to the spirits and the innate heat are appropriate to the blood alone; to say nothing of what is so wonderfully striking in the egg before aught of the embryo has appeared, and in the perfect and developed embryo also. To be sure, the blood, considered absolutely and by itself outside the veins and regarded as consisting of elements[453] and as composed of different parts,--some thin and serous, some thick and solidified,--is termed 'cruor' and is possessed of very few virtues, and those obscure. But the blood, when present within the veins as a part of the body, a generative part, too, and endowed with soul, being the soul's immediate instrument and primary seat--the blood, seeming also to have a share of another diviner body and being suffused with divine heat, certainly acquires extraordinary powers, and is analogous to the element of the stars. As spirits the blood is the hearth, the Vesta,[454] the household deity, the innate heat, the sun of the microcosm, the fire of Plato;[455] not because it shines, burns, and destroys, like common fire, but because it preserves and nourishes and increases its very self by its perpetual wandering motion. Moreover, the blood deserves the name of spirits because, primarily and before all other parts, it abounds in radical moisture, that is, in the final and most immediate form of nourishment; and the same fare wherewith the blood itself is nourished is made ready by it and given out to all other parts while it is coursing perpetually through the entire body. Indeed, the blood nourishes, fosters, and keeps alive all the parts which it constructs and adjoins to itself, even as the heavenly bodies above, especially the sun and moon, impart life to what is below, while they continue in perpetual circulation. Since, therefore, the blood acts beyond the powers of the elements and is potent with those virtues aforesaid, and also is the instrument of the supreme workman, no one ever will give praise enough to its wonderful and divine faculties."[456] Let us end these studies by picturing to ourselves the memorable figure of the small white-haired man ensconced in one of his favorite nooks on the leads of his brother's house, musing upon the mystery of the circulation, and linking it with that of "The shining powers, conspicuous afar Against the ether, which to mortals bring Winter and summer."[457] NOTES [1] In the present paper frequent references will be made to the writings of Harvey, Galen, Aristotle, and Hippocrates. Citations from these authors will be made from the following editions:--