re capable of being altered into a
Matter fit to breed this Disease: because this is the Case of every one
who is sick of it, the Humours in him being corrupted into a Substance
which will _infect_ others. And it is not improbable, that the volatile
Parts with which Animals abound, may in some ill States of Air in the
sultry Heats of _Africa_ be converted by Putrefaction into a Substance
of the same kind: since in these colder Regions, we sometimes find them
to contract a greater Degree of Acrimony than most other Substances will
do by _putrefying_, and also more dangerous for Men to come within the
reach of their Action; as in those pernicious, and even poysonous
Juices, which are sometimes generated in corrupted Carcasses: Of which I
have formerly given one very remarkable Instance[48], and, if it were
necessary, many more might be produced, especially in _hydropic Bodies_,
and in _cancerous Tumors_. Nay more, we find _animal Putrefaction_
sometimes to produce in these _Northern_ Climates very fatal Distempers,
though they do not arise to the Malignity of the true _Plague_: For such
_Fevers_ are often bred, where a large Number of People are closely
confined together; as in _Goals_, _Sieges_, and _Camps_.

AND perhaps it may not be here amiss to remark, that the _Egyptians_ of
old were so sensible how much the _Putridness_ of dead Animals
contributed towards breeding the _Plague_, that they worshipped the Bird
_Ibis_ for the Service it did in devouring great Numbers of Serpents;
which they observed did hurt by their Stench when dead, as well as by
their Bite when alive[49].

BUT no kind of _Putrefaction_ is ever hightened in these _European_
Countries to a degree capable of producing the true _Plague_: and we
learn from the Observation of the _Arabian_ Physicians, that some
Indisposition of the _Air_ is necessary in the hottest Climates, either
to cause so exalted a Corruption of the forementioned Substances, or at
least to enforce upon Mens Bodies the Action of the _Effluvia_ exhaled
from those Substances, while they putrefy. Both which Effects may well
be expected from the sensible ill Qualities of the _Air_ before
described, whenever they continue and exert their Force together any
considerable time.

WHAT I have here advanced of the first Original of the _Plague_, appears
to me so reasonable, that I cannot enough wonder at Authors for quitting
the Consideration of such manifest Causes for _Hidden Qualities_; suc