The small-pox hath been generally ranked among inflammatory diseases, and certainly with propriety, if we consider it only in it’s first stage; but that, in it’s natural progress, it becomes a putrid disorder, is indisputably true. Let us now suppose a number of patients ill of a malignant putrid disease, the jail fever for instance. Let us suppose these unhappy beings pent up in the close ward of an hospital, swallowing hot medicines, and denied the use of fresh air. In such a state the disease would certainly exert it’s utmost virulence, and very few of the patients would recover. Let us farther suppose a number of patients, in a contiguous ward, receiving the infection from the others; but let us imagine their medicines less inflammatory, and the air less confined: is there a physician here present, who has the least doubt that the disorder, in this case, would be less malignant and less fatal? Let us yet farther suppose a third ward, contiguous to the second, and the patients, infected from the second ward, treated more on the anti-phlogistic and antiseptic plan, and particularly indulged with fresh air: such patients, I say, having caught a milder disease, and being more rationally treated, would more generally escape. But if we carry our supposition still farther, as we gradually recede from the first ward, we shall find, by a parity of reasoning, that the disease will at last retain no more of it’s original malignity, than is barely sufficient to communicate the infection. The disorder will now assume so mild an aspect as hardly to appear of the same _genus_ with that from which it originally sprung. What hath been said of the jail fever, will evidently apply to the small-pox. We Europeans received it a malignant, a fatal disease; the fatality and malignancy of which, by the general practice of nurses, and, indeed, of most physicians, hath, perhaps, been rather increased than diminished: for, if an infectious disease may be rendered more mild by judicious treatment, it is no less certain, that a mild disorder may, by a series of improprieties, be gradually raised to such a height of virulence, as to assume a new aspect, and exhibit phenomena so different from those of it’s parent disease, that, in the end, it will constitute a new genus. If this be admitted as a possibility, perhaps it might be no difficult matter to trace many of our disorders to their origin, and to prove, that a considerable number are of our own creation; they are the offspring of medicine, the children of dulness or chimera, begotten upon old women.