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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.