Nine books of physick and chirurgery written by that great and learned physitian, Dr Sennertus. The first five being his Institutions of the whole body of physick: the other four of fevers and agues: with their differences, signs, and cures.

CHAP. I. Of the Nature of a Fever.

THat which is called by the Latines a Fever, * 1.1 by the Greeks (from fire) is called the fiery di∣stemper; Hippocrates plainly calls it fire, if it be very vehement, as being by the consent of all men a hot distemper; For although some Ger∣mans call it Daskalte, yet that appellation belongs not to e∣very Fever, neither doth it express the nature of a Fever, but only signifieth Cold, An intermitting Fever may be so called.

A Fever is a hot distemper of the whole body, atising from heat, kindled contrary to nature in the heart, * 1.2 and by the me∣diation of the Blood and Spirits, conveyed through the veins and arteries to all the parts, and hindring natural actions, un∣less it be prevented.

For a Fever is generated, when (as Galen 1. Aphor. 14. hath it) The native heat is become fiery; * 1.3 For seeing that all the parts of the body have a certain temperature, and all of them are actually hot, every one according to its own degree, and thereby are rendered fit to perform natural actions; If

in the heart, from whence the vital heat is diffused over all the parts of the body, each part receiving its due temper from thence, a certain preter-natural heat be kindled and spread o∣ver the whole body, so that to the natural temperature of the parts some degrees of preter-natural heat are added, and that actual heat shall be increased; a certain excess of heat and a hot distemper is kindled in the whole body, which is called a Fever. Which distemper indeed formaliter, as some say, is contrary to nature, and is called a Fever; but materialiter 'tis not altogether contrary to nature, for unless there had been before some degrees of natural heat extant, the superveni∣ent heat could not constitute this degree of heat.

And indeed a hot distemper only constitutes a Fever; * 1.4 for although all fevourish heat tend to driness, yet that driness is not sickness in all Fevers, neither is the body by fevourish heat rendred unfit to perform its natural actions, it is so by dri∣ness in every Fever that the natural actions are hindred; but although the fevourish heat always tend to driness, yet often∣times the disposition of the body wherein that heat acteth, and moisture therewithal, hinders the production of a disease by driness.

The adequate Subject of a Fever is the whole body, * 1.5 or cer∣tainly most of its parts, but the principal is the heart, as being that wherein that heat is first kindled, and from thence communicated to all the other parts of the body, unless it be hindred; nor can a Fever be generated, unless the heart first become hot. Indeed the whole body is the Subject of a Fever in regard of the similiar parts, and as it is indued with actual heat, which is as it were kindled by the innate and influent heat; For this heat when it is changed and converted into a fiery heat from a temperate and moderate, a Fever is stirred up.

The immediate cause of a Fever is heat kindled in the heart contrary to nature, * 1.6 and diffused over all the body; For as the heart whilest it is well and according to nature, is the foun∣tain of natural heat, and disperseth the same over all the bo∣dy, so if it grow hot contrary to nature, it distributes that unnatural heat over all the parts. For although a Fever may be kindled by the inflamation of other parts likewise, yet that happens not unless that heat be first sent to the heart, and af∣terwards from thence to all the parts of the body, whence it comes to pass that in every Fever the Pulse is changed. Ne∣vertheless every kind of heat in the heart is not sufficient to

cause a Fever, but such a kind of heat it ought to be, as can cause such a hot disease as can hinder the performance of natu∣ral actions.

Whence 'tis manifest that a Fever is one thing, * 1.7 and a fea∣vourish heat another thing. A Fever properly is that hot di∣stemper which happens in the living parts of a body, and ren∣ders them unable to act; but the fevourish heat is also in the humors and spirits, and stirrs up that hot distemper of the bo∣dy, which constitutes the essence of a Fever.

Notes

• * 1.1

  The name. of a Fever
• * 1.2

  Its defini∣tion and nature.
• * 1.3

  Generati∣on of it.
• * 1.4

  Driness is no part of the Essence of a Fever.
• * 1.5

  The Sub∣ject.
• * 1.6

  The proxi∣mate cause.
• * 1.7

  A Fever and feve∣rish heat differ.