The line of its progression is taken from the observation of disease, and from that alone. Wherever disease appears, there it is said that contagion has been carried or conveyed; and as a proof of that position, it is gravely maintained, that disease invariably breaks out where there are houses, and where communication is likely to be going on in some way or other. This most extraordinary fact proves what must certainly be thought not less extraordinary, that it appears in the abodes and habitations of men. But where else is disease, we would ask, to manifest itself, if among men at all, if not where alone they are to be found?—surely not among deserts uninhabitable, or on the frosty summit of an iceberg? It is true that in the course of an epidemic, such as the cholera, one country suffers before another; but there is no alternative to such a course if they are not to be simultaneously affected. And it signifies nothing that communication subsists between them. One part of a country, too, is ravaged first, then another, and so on—one town then another—one part of a town, and after it another part. But it is evident, that if disease is to begin at all, it must begin somewhere, and if all parts are not to be seized on the same instant, that one will have precedence of another, and so on. Springing and propagating, from whatever causes, that character must hold, and surely it is wrong to hold a feature common to the effects of many causes as decisive evidence of the operation of one, and of one only. The harvests of Europe begin in one country, sooner than in another. In many, harvest is earlier than in England, but it is never surmised that when that process begins in the latter country, that it is through the mediation of some such influence as contagion. It begins in England, too, it might be shewn, in places having communication with foreign countries. Nay, it might also be proven that the parts in which it in general commences are at the coast, where it is well known ships are wont to appear. Were such an insane supposition made, the most obvious facts would necessarily be laid aside; but such gross blindness would not, we are satisfied, be much greater, than when the process of diseased action, marked out in an epidemic, is attributed to contagious atmosphere alone. In the case of the harvest, it would argue a forgetfulness of the object held in view when the seed was sown,—in that of disease, an ignorance of the effects to be expected from the sowing of the seeds of pestilence (the exposure to the common epidemic influences alluded to above), in the first, an insensibility to the influence of climate, intensity of sun’s rays, the quality of the soil, &c.:—And in the other, a blindness to the operation of circumstances not less potent, such as the time of application of the causes, the condition of the body, and the presence or absence of moral adjuvants.