Chapter XXIX

What is the Cause of a Fever, or Whether it is an Affection of the Body Annexed to a Primary Passion

Erasistratus gives this definition of a fever: A fever is a quick motion of blood, not produced by our consent, which enters into the vessels, the seat of the vital spirits. This we see in the sea; it is in a serene calm when nothing disturbs it, but is in motion when a violent preternatural wind blows upon it, and then it rageth and is circled with waves. After this manner it is in the body of man; when the blood is in a nimble agitation, then it falls upon those vessels in which the spirits are, and there being in an extraordinary heat, it fires the whole body. The opinion that a fever is an appendix to a preceding affection pleaseth him. Diocles proceeds after this manner: Those things which are internal and latent are manifested by those which externally break forth and appear; and it is clear to us that a fever is annexed to certain outward affections, for example, to wounds, inflaming tumors, inguinary abscesses.