TO this Cause, ’tis very probable, is owing the Frequency of the Plague at _Grand Cairo_ in _Egypt_, and in the Island of _Sardinia_, as _Pæusanias_ and others relate: Although indeed _Prosper Alpinus_[10] charges a great deal of the Cause of that at _Cairo_, upon their continual Commerce with such Nations as are seldom without such infectious Diseases. And for this Reason it is, that we find all those Countries, which most abound with Swamps and Standing-Waters, to be most unhealthful, especially in the hottest Seasons; except, as in several Parts of _Italy_, such Lakes have any Communication with the Sea, or some large Rivers. To this purpose _Piso_[11] frequently observes those Places to be most subject to such Calamities, where there are constant Heat and settled Calms, as such a Temperament of Air most disposes Bodies to Putrefaction and Corruption, as in St. _Thomas Island_, and _Guinea_: And, on the contrary, that notwithstanding the Intenseness of Heat, if the Fluids are but agitated by Winds, Tides, and Currents, there is little Danger of such Diseases; and the less still, the more regular and constant the Seasons are upon other Accounts: By which Means it is, that between the _Tropicks_, and even under the _Equator_, it is very healthful. UNDER this Head it may not be improper to observe, that too scanty and mean a Diet, and Feeding upon unripened and unsound Fruits, are frequently charged with a Share in Mischiefs of this kind. _Josephus_[12] and _Julius Cæsar_[13], amongst Historians; _Forestus_,[14] and several other physical Writers, give Accounts of Plagues from the like Causes. _Galen_[15] is very positive in this Matter; and in one Place[16] accuses his great Master _Hippocrates_ with Neglecting too much the Consequence of a bad Diet, and ascribing some Mischiefs arising from thence to a bad Air. And upon this is grounded the common Opinion of a _Plague_’s following a _Famine_; in which Circumstances, the poorer sort, who feed meanest, generally suffer most, as it frequently happens in long Sieges, and Armies ill supplied with Provisions. Thus Travellers report, that _Surrat_ in the _East-Indies_ is seldom or never free from a Plague, which is ascribed to the mean Diet of the Natives, who are _Banians_, and feed on little else than Herbs, Water, Rice, and such like pitiful Fare; for it is observed, that the _Europeans_ who trade there, are in no Danger of being infected, because they feed well on Flesh, and drink Wine, which secures them against those malignant Diseases.