Three Books on Life by Marsilio Ficino

First published in 1489, De Vita Libri Tres comprises three volumes: the first book is about physical health, the second is about prolonging life, and the third is about astral influences. The work focuses not on the soul or body, but on the spiritus, which is described early on:"Only the priests of the Muses, only the hunters after the supreme good and truth are so negligent (alas) and so unfortunate that they seem utterly to neglect that instrument by which they can, in a way, measure and grasp the whole world. An instrument of this sort is the spirit, which by the physicians is defined as a certain vapour of the blood, pure, subtle, hot and lucid. And, formed from the subtler blood by the heat of the heart, it flies to the brain, and there the soul assiduously employs it for the exercise of both the interior and exterior senses. Thus the blood serves the spirit, the spirit the senses, and finally the senses reason." The book's thrust depends on the tension Ficino tries to resolve in