Chap. 1. Of a Pestilential Feaver.
That Feaver is termed Pestilential, which does afflict Nature not only by a bare distem∣per, or by heat arising from putrefaction, but also with a Maliguant and venemous quality. This is wont to be for the most part Popular and Epidemical; so that many are at the same time sick thereof: yet somtimes it is sporadick or single afflicting but here and there one, which arises from evil Humors that have attained a venemous quality.
It is likewise Contagious, so that it may be caught not only by means of the common Cause, Viz. Corruption of the Air or Diet; but also by Conversing with those that are sick.
It is also commonly called a Malignant Feaver, whereas many diseases are termed Malig∣nant. by reason of their evil and cruel symptomes in which no venemous quality is found, in which alone the essence of a Pestilential disease consists.
In what Feaver soever therefore, this same venemous quality is found, whether it be a di∣ary, an hectick, or a putrid Feaver, it is rightly termed Pestilentiall: although a dairy and hect∣ick are much controverted, touching which consult the Authors.
Now this same venemous quality ariseth from the corruption of Homors, which consists not in a bare change of the temperament, or in ordinary putresaction, such as is found in putrid Feavers; but in a destruction of the whol Nature and Essential substance of the same Humors. As Wine when it is turned an iosipid tastless Liquor, is totally and essentially corrupted; but when it becomes vinegar, it is said simply to putrefie.
And a Pestilentiall Feaver differs from the Plague as a species or sort differs from the genus or kind, because there may be a Pestilence without a Feaver, as Hippocrates hath taught us in his third Epidem, in many places; and also Galen in his Exposition of the said Book. and in his ninth Book, de Medic. Facultatib. Cap. de Terra Samia. And this is sutable to Reason forasmuch as the venemous Quality is not necessarily attended with putrefaction, which is the Cause of a Feaver. For that same venemous qualitie may be produced in the Humors, by a perfect corruption of their substance, and introduction of a new form, of which that vene∣mous qualitie depends. And certain it is, that so oft as a new from is introduced, the former is corrupted; unto which mutations there are requisite preparatorie alterations, but not putrefaction so that Humors may undergo such a corruption without putrefaction; but because the Hu∣mors of our body are very liable to putrefaction, they can rarely undergo so great a corruption, without the Intervention of putrefaction likewise; wherefore those Pestilences are very rare, which are not accompanied with a Feaver: Yea verily and by an intense, profound and for∣did (as they are wont to say) putrefaction, such a Corruption as that of the Plague is wont to