body, confusing arteries, veins and nerves, and speaking vaguely of the muscles as "flesh." But when we come to study his observations on the natural history of disease as presented in the living subject, we recognize at once the presence of a great clinical physician. Hippocrates based his principles and practice on the theory of the existence of a spiritual restoring essence or principle, [Greek: physis], the _vis medicatrix naturae_, in the management of which the art of the physician consisted. This art could, he held, be only obtained by the application of experience, not only to disease at large, but to disease in the individual. He strongly deprecated blind empiricism; the aphorism "[Greek: he peira sphalere, he krisis chalepe]" (whether it be his or not), tersely illustrates his position. Holding firmly to the principle, [Greek: nouson physies ietroi], he did not allow himself to remain inactive in the presence of disease; he was not a merely "expectant" physician; as Sydenham puts it, his practice was "the support of enfeebled and the coercion of outrageous nature." He largely employed powerful medicines and blood-letting both ordinary and by cupping. He advises, however, great caution in their application. He placed great dependence on diet and regimen, and here, quaint as many of his directions may now sound, not only in themselves, but in the reasons given, there is much which is still adhered to at the present day. His treatise [Greek: Peri aeron, hydaton, kai topon] (_Airs, Waters, and Places_) contains the first enunciation of the principles of public health. Although the treatises [Greek: Peri krisimon] cannot be accepted as authentic, we find in the [Greek: Prognostikon] evidence of the acuteness of observation in the manner in which the occurrence of critical days in disease is enunciated. His method of reporting cases is most interesting and instructive; in them we can read how thoroughly he had separated himself from the priest-physician. Laennec, to whom we are indebted for the practice of auscultation, freely admits that the idea was suggested to him by study of Hippocrates, who, treating of the presence of morbid fluids in the thorax, gives very particular directions, by means of succussion, for arriving at an opinion regarding their nature. Laennec says, "Hippocrate avait tente l'auscultation immediate." Although the treatise [Greek: Peri nouson] is doubtfully from the pen of Hippocrates, it contains strong evidence of having been the work of his grandson, representing the views of the Father of Medicine. Although not accurate in the conclusions reached at the time, the value of the method of diagnosis is shown by the retention in modern medicine of the name and the practice of "Hippocratic succussion." The power of graphic description of phenomena in the Hippocratic writings is illustrated by the retention of the term "facies Hippocratica," applied to the appearance of a moribund person, pictured in the _Prognostics_.