merbroek_ deserves notice in this Place; That, part
of a Family removed into a Town free from the _Plague_, was observed by
him to be taken ill of it soon after the part left behind in the
diseased Town fell sick: which certainly could scarce have happened,
unless a Communication between the Healthy and the Sick, by Letters or
otherwise, was capable of causing it[23]. Of the same Nature is a
Circumstance recorded by _Evagrius_ of the _Plague_, which he describes,
and what, he owns, surprized him very much: That, many of those, who
left infected Places, were seized with the _Plague_ in the Towns to
which they had retired, while the old Inhabitants of those Towns were
free from the Disease[24]. But to multiply Proofs of a thing so evident,
is needless; innumerable are at hand, and several will occasionally
occur in the following Parts of this Discourse, when we come to speak in
particular of the ways, by which this Infection is conveyed about. I
shall therefore say no more in this Place, but only, that all the
Appearances attending this Disease are very easily explained upon this
Principle, and are hardly to be accounted for upon any other. We learn
from hence the reason why when the _Plague_ makes its first Appearance
in any Place, though the Number of Sick is exceeding small, yet the
Disease usually operates upon them in the most violent manner, and is
attended with its very worst Symptoms. Now was the Disease produced not
by imported _Contagion_, but from some Cause, which had its Original in
the diseased Place, and consequently from a Cause gradually bred, the
contrary must happen: the Diseased would at first not only be few in
Number, but their Sickness likewise more moderate than afterwards, when
the morbific Causes were raised to their greatest Malignity. From the
same Principle we see the reason, why People have often remained in
Safety in a diseased Town, only by shutting themselves up from all
Communication with such, as might be suspected of giving them the
Disease. When the _Plague_ was last in _England_, while it was in the
Town of _Cambridge_, the Colleges remained entirely free by using this
Precaution. In the _Plague_ at _Rome_ in the Years 1656 and 1657, the
_Monasteries_ and _Nunneries_, for the most part, defended themselves by
the same Means[25]: Whereas at _Naples_, where the _Plague_ was a little
before, these _Religious Houses_, from their Neglect herein, did not
escape so well[26]. Nay the Infection