THIS Book having at first been written only as a Plan of Directions for preserving our Country from the =Plague=[1] was then very short and concise. An Act of Parliament being immediately after made for performing =Quarantaines= &c. according to the Rules here laid down, it passed through seven Editions in one year without any Alterations. I then thought proper to make some =Additions= to it, in order to shew the Reasonableness of the Methods prescribed, by giving a more full Description of this Disease, and collecting some Examples of the good Success which had attended such Measures, when they had been put in Practice. At the same time I annex'd a short Chapter relating to the Cure of the Plague; being induced thereto by considering how widely most Authors have erred in prescribing a Heap of useless and very often hurtful Medicines, which they recommend under the specious Titles of =Antidotes=, =Specifics= and =Alexipharmacs=: hoping that the great Resemblance, which I had observed between this Disease and the =Small Pox=, would justify my writing upon a Distemper which I have never seen. INDEED the =Small Pox= is a true =Plague=, tho' of a particular kind, bred, as I have shewn all Pestilences are, in the same hot =Egyptian= Climate, and brought into =Asia= and =Europe= by the way of Commerce; but most remarkably by the War with the =Saracens=, called the =Holy War=, at the latter end of the eleventh and the beginning of the twelfth Century[2]. Ever since which time the morbific Seeds of it have been preserved in the infected Cloaths and the Furniture of Houses: and have broken out more or less in all Countries, according as the hot and moist Temperature of the Air has favoured their Spreading and the Exertion of their Force. The =Measles= is likewise a =Plague sui generis=, and owes its Origin to the same Country. I have now revised my little Work once more: and though I cannot find any reason to change my Mind as to any material Points which regard either the =Preventing= or the =Stopping= the Progress of =Infection=; yet I have here and there added some new =Strokes= of Reasoning, and, as the Painters say, retouch'd the =Ornaments=, and hightened the =Colouring= of the =Piece=. THE Substance of the long Preface to the last Edition is as follows.