We have abundant reason for the belief that nothing is fortuitous; but, on the contrary, that everything in this world of ours is the effect of design; all things around us bearing evident stamp of the skill and beneficence of its Omnipotent Author. “Thus at thy potent nod, EFFECT and CAUSE Walk hand in hand accordant to thy Laws; Rise at Volition’s call; in groups combined, Amuse, delight, instruct, and serve mankind.” The histories of epidemic pestilences or diseases--because of the vast numbers of persons on whom they seize at one and the same time, and also because of their intensity and destructiveness,--are not only of greater importance to mankind than are the generality of maladies, but they are also of deep interest in as far as concerns questions of pathology. Epidemics are also exceedingly interesting in a physical and moral point of view,--their histories, and the investigation of their causes, leading to an insight into the organism of the world, in which the sum of organic life is subjected to the greater powers of nature; for it would appear, as far as human knowledge extends, that all organized bodies, from a variety of causes as dissimilar as they are complicated and numerous, are more or less susceptible of change and decay. Thus we see disease assail and carry off mankind at all times and in all regions: murrain is destructive of dumb animals, while blight spares not the vegetable kingdom, from the sturdiest oak to the most diminutive herbage; in fine, all nature is subjected, in various degrees, to the devastating tendency of the elements in their general evolutions in the mundane economy, based on immutable laws, arising from original and supreme provision: “Wonder-working hand, ---- in majestic silence sways at will The mighty movements of unbounded nature.” Considering that epidemic pestilences or diseases have been from time immemorial more destructive of mankind than all other maladies, or than even famine and the sword combined, it is somewhat surprising that a comprehensive and efficient investigation of such an important class of diseases, founded on enlarged and scientific views, has never yet been made,--in fact, has scarcely ever been attempted. Such apathy to minute enquiry into the nature and causes of epidemics, and the indifference evinced to every-day occurrences, so much attended to by the ancients, is culpable in the extreme; for nothing can be more injurious to the cause of truth, or tend more to retard scientific pursuits, than such disregard of the nature of things, for daily experience alone is sufficient to show that every effect in the physical world has an antecedent cause, which is at all times open to experiment and investigation, and which, however obscure at first, may often be explained and understood by means of close observation and steady perseverance in our researches.