_Hippocrates_, on the other Hand, undertakes only to relate the Constitution of the Year when _Plagues_ and _Fevers_ were very frequent; he never thought of making any particular Constitution, or the Weather in it, the Cause of Plagues universally: If he had, Experience should have shewn the contrary, to which he would have submitted. But not to enter into any other Constitutions that might happen in _Greece_, Experience cries loudly against this _Hypothesis_ of Dr. _Mead_; since we know that _hard_ and _continued frosty_ Weather produces the Pestilence, most commonly, in our Northern Climates. The Winter 1664, was a continued Frost all through, as Dr. _Hodges_ informs us; yet the Plague broke out in the _Christmas_ time, when it was in its _Strength_. The Plague in _Dantzick_, mention’d by Dr. _Mead_, was in the Winter, when every thing was bound up with a severe _Frost_; yet so violent was this Plague, that it bred the _Dunkirk-Fever_ in the Fag-end of it, as Dr. _Mead_ learnedly conjectures. So that the Pestilence frequently, and most commonly, happens in a Season very opposite to what the Doctor finds necessary for breeding _Infection and Corruption_, the _Fore-runners_ of a Plague. From all this Account it is manifest, that we hitherto know nothing of _Contagion_, nor of any Corruption convey’d into Air, which it is to foment and cherish, to beget or propagate the Pestilence; as also that this Notion of Contagion taken up and espoused by later Physicians, is very ill supported by them, and still worse by Dr. _Mead_, who is little acquainted with their Opinions, so common and obvious in Books of Physick. And therefore as he has been very unhappy in discovering the _Change_ in Air that makes it infectious; we will try for better Success, in his discovering the _Means_, whereby it _communicates its noxious Quality to other Bodies_.