I have insisted more at large upon the =Infection= of this Disease, than I could ever have thought needful at this time, after =Europe= has had Experience of the Distemper for so many Ages; had I not been surprized by the late Attempts of some Physicians in =France= to prove the contrary, even while they have the most undeniable Arguments against them before their Eyes. In particular, I cannot but very much admire to see Dr. =Chicoyneau=, and the other Physicians, who first gave us =Observations= on the =Plague=, when at =Marseilles=, relate in the =Reflections=, they afterwards published upon those Observations, the Case of a Man, who was seized with the =Plague=, upon his burying a young Woman dead of it, when no one else dared to approach the Body; and yet to see them ascribe his Disease, not to his being =infected= by the Woman, but solely to his Grief for the Loss of her, to whom he had made Love, and to a =Diarrhoea=, which had been some time upon him[3]. No question but these concurred to make his Disease the more violent; and perhaps even exposed him to contract the =Infection=: but why it should be supposed, that he was not =infected=, I cannot imagine, when there was so plain an Appearance of it. I am as much at a Loss to find any Colour of Reason for their denying =Infection= in another Case, they relate, of a =young Lady= seized with the =Plague=, upon the sudden Sight of a =PESTILENTIAL TUMOR=, just broke out upon her Maid; not allowing any thing but the Lady's Surprize to be the Cause of her Illness[4]. THE Truth is, these Physicians had engaged themselves in an =Hypothesis=, that the =Plague= was bred at =Marseilles= by a long Use of bad Aliment, and grew so fond of their Opinion, as not to be moved by the most convincing Evidence. And thus it mostly happens, when we indulge Conjectures instead of pursuing the true Course for making Discoveries in Nature.