AS the ordinary Course therefore of producing Fevers is by disordering the Blood first in Quality, with such Mixtures as coagulate it, that is, as make it unequally fluid, some Parts being thinner, and others thicker than natural; so by these extreamly subtile _Effluvia_, in a _Contagion_, the Spirits are destroyed in their natural Texture, and the more rigid and saline Parts, by a Combination with the venomous _Spicula_, changed into Dispositions destructive of that Constitution they were before destined to preserve. Whosoever then considers what must be the necessary Consequences of such an immediate Depravation and Change in that Fluid, which is an absolute Requisite to all animal Action, will not at all wonder at any of the Affections which are commonly enumerated as the _Concomitants_ of a Contagion; and a tolerable Acquaintance with the OEconomy, by the Help especially of the Authors before referred to on _Fevers_ and _Poisons_, will enable any one to account severally for their Production. THIS then being the Case of a _Contagion_, that a Person having a Fever, critically throws off poisonous _Effluvia_, which were generated during such irregular Motions of the animal Fluids, insomuch as to diffuse for some Distance round, what will infect other Persons within their reach; and that so many have got this Infection, that no Part of the Air, for some Tract of the Country together, is free from them; the poisonous _Atmospheres_, if they may be so termed, of the infected, extending and mixing into one universal, common _Contagion_; this, I say, being the Case here under Examination, why any at all survive, must be owing either to the Goodness of their Constitution, or to proper Means to defend against its Infection, or to conquer it when received; which naturally brings us to consider these two important Ends, of _Preservation_ and _Cure_. AS for the _First_ of these, the common Experience, of meaner People being mostly carried off, admonishes all to live upon as nutritive and generous a Diet as can be procured; and such Things as not only yeild due Nourishment, but Plenty of Spirits, and what easily perspires. For there are many Things of good Nourishment, that are not easily perspired; such as all light and viscid Substances, as Pork, Fish, and the like, which therefore are very apt to go into Fermentation, and generate Corruption; in short, whatever even the common People have Notions of, as apt to bring Surfeits, ought to be avoided, and such Means of Subsistance complied with, as generate a warm, rich Blood; and in Proportion to the Ways of Living at other Times, should every one, except those who accustom themselves to Riot and Excess, indulge himself at a higher Rate.