ON the other hand, I would not be understood to call every _Fever_ a _Plague_, which is followed by Eruptions resembling these here mentioned: For as every _Boil_ or _Pustule_, which breaks out upon the Skin, is not an Indication of the _Small Pox_, nor every Swelling in the _Groin_ a _Venereal Bubo_; so there are _Carbuncles_ not Pestilential, and other Fevers, besides the _Plague_, which have their Crisis by _Tumors_ and _Abscesses_, and that sometimes even in the _Parotid_ or other Glands. There is indeed usually some difference between these Swellings in the _Plague_, and in other Fevers, especially in the time of their coming out: for in the _Plague_ they discover themselves sooner than in most other Cases. But the principal difference between these Diseases, is, that the Plague is infectious, the other not; at least not to any considerable Degree. AND this leads me to another Character of this Disease, whereby it is distinguished from ordinary Fevers, which is the _Contagion_ accompanying it. This is a very ancient Observation. _Thucydides_ makes it a part of his Description of the _Plague_ at _Athens_[19]; and _Lucretius_, who has almost translated this Description of _Thucydides_, dwells much upon it[20]. _Aristotle_ makes it one of his[21] _Problems_, How the _Plague infects_ those who approach to the Sick. And what is of more Consequence, _Galen_ himself is very clear in it[22]; for he has these words: +hoti syndiatribein tois loimôttousin episphales, apolausai gar kindynos, hôsper psôras tinos+, _&c. that it is unsafe to be about those, who have the Plague, for fear of catching it, as in the Itch_, &c. Indeed this is a thing so evident, that we find it at present the current Opinion of all Mankind, a very few Persons only excepted, who have distinguished themselves by their Singularity in maintaining the opposite Sentiment. And it is something strange that any one should make a Question of a thing so obvious, which is proved sufficiently by one Property only of the Disease, that whenever it seizes one Person in a House, it immediately after attacks the greatest part of the Family. This Effect of the _Plague_ has been so remarkable at all times, that whoever considers it well, cannot possibly, I think, have any Doubt remaining, or require any stronger Argument to convince him, that the Disease is infectious. For this very reason the _Small-Pox_ and _Measles_ are generally allowed to be _contagious_; because it is observed, that when either of these Diseases is got among a Family, it usually seizes successively the greatest part of that Family, who have not had it before: at least if such in the Family hold free Communication with the Sick. And by the same Argument the _Plague_ must be concluded to be infectious likewise. It cannot be pretended, that this is occasioned in the _Plague_ from this only, that the sound Persons are render'd more than ordinarily obnoxious to the unhealthy