doctrines, we find Hippocrates in the first place investigating the influence of surrounding circumstances on the health and diseases of the living body. In the book on Ancient Medicine he opposes those who would attribute all diseases to a single cause, whether heat or cold, or dryness or moisture. He founds his system on realities-on observation, the records of science, and the deductions of sound reasoning. Adopting from the schools of philosophy the doctrine of the primitive elements, and that of the primitive humors which was derived from this, he sees in the human body the humors undergoing changes in accordance with the conditions of health and disease. He is led to believe that health is maintained by the equable proportion and intermixture of the humors, and that disease is the result of their inequalities. He admits that during their changes the disordered humors undergo a process of coction by which they may be restored to their healthy condition; and as time is requisite for effecting this process he undertakes to show how the critical discharge is brought about; and to establish the days within which it is to be expected.

In the book on Airs, Waters, and Places, he inquires into the effects of particular exposures, of the seasons and their vicissitudes; the influence of winds and the properties of waters. He alludes to the diseases prevalent in different places and during different times of the year. He contemplates the moral and physical characteristics of different nations, resulting from the climate, locality, and other influences to which they are subject. He rejects the

superstition of his times in reference to supernatural agencies. He holds that no one disease is more the result of divine wrath than another, and that all of them originate from natural causes. The predispositions resulting from the different periods of life, he studies with equal attention. He holds that the innate heat of the body is at its maximum during infancy, at its minimum in old age; and that each particular phase in this quality, like the influence of the sun in different seasons of the year, predisposes to its particular class of ailments. Among the agencies applying more especially to the individual, he dwells with becoming attention on diet and exercise; showing how excess or deficiency in the one or the other, may prove the prolific source of dis

ease.

In connection with this theory of innate heat, and that of the humors, he lays much stress on the doctrine of Coction; implying by this term, the changes which the disordered humors undergo, pre. paratory to their elimination. So long as they are floating about in a state of crudity, the disease continues in full intensity; but when they are properly elaborated, the disease reaches its crisis, and they are discharged, either by the spontaneous effort of nature, or by the aid of medicine acting in subservience to nature's laws. Where the crisis cannot thus be effected by the removal of the offending humors from the body, it may be brought about by their localization in particular organs or parts of the body, as by the development of a critical abscess, by an erysipelatous inflammation, by a diseased joint, or

by a circumscribed mortification. But where the crisis is not to be effected either by elimination or localization, the disease is said to be incurable, as in cancer. The critical discharges, where the disease is general, may be effected either by perspiration by the flow of urine, by alvine dejections, by emesis, or by expectoration.

The cycle of changes by which the crisis is effected, he holds to be usually completed within certain definite periods of time; and the days at which the crisis may be anticipated, he calls Critical Days. He dwells with much care on every circumstance likely to retard or accelerate the critical period, and on the dangers to be apprehended during those critical days, regular or irregular, in which the disease is not adjudicated. The study of the various appearances pointing to the probable result of the disease, to the character of the crisis, and to the time at which this may be expected, is summed in his doctrine of Prognosis. By this was meant something more than is implied in the etymology of the term, and much more than is at present understood by it. In the estimation of the early Grecians, Prognosis was the crowning department of medical science; furnishing them the key for explaining the past and present, as well as the yet to be developed circumstances of disease; and pointing out to them what should be left to the efforts of nature, and what might require the interference of art, where nature, unassisted, was unable to bring the disease to a favorable issue.

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It is further worthy of remark, that in the Hip

pocratic school, the condition and changes of the humors, the crisis, the critical discharges, the critical days, and above all, the prognostications, were studied in the abstract, or as connected only with the condition of the living body, without reference to the distinctive traits of individual diseases. With them, prognosis was the application of medical science for determining the value of general manifestations, not of particular morbid processes. It held the same relation to diseases in general, that diagnosis, in our use of the term, now holds to individual ailments.

In his book of Prognostics, Hippocrates dwells only on the generalities of disease. In his Epidemics he describes what he himself had witnessed, even to the progress and results of individual cases, still studied in the same spirit of generalization, without reference to the characteristic features of individual, much less of specific diseases. In his book on Regimen in Acute Diseases, he appreciates his therapeutics as subservient to the indications of nature, whose efforts it becomes the physician to assist, but never to interrupt. The teaching of Hippocrates and his disciples, is thus shown to have been theoretical, yet founded on what, at the time, appeared to them to be legitimate inferences from the observation of facts,-of facts carefully studied and cautiously generalized. And while the whole science of physiology, and nearly the whole of anatomy, remained yet to be explored, we are not so much to be surprised at their theories, as that these theories, derived almost exclusively from the

study of external appearances, should have been so very near the truth.

As already intimated, several treatises in the Hippocratic collection must have emanated from writers not of the school of Cos, but who are to be considered either among the contemporaries of Hippocrates, or of his more immediate descendants. The book on Regimen for Persons in Health, has been ascribed to Philiston, who was celebrated for his acquaintance with anatomy, and who flourished about the time of Plato. The treatise on the Seventh Month Foetus, has been attributed to Diocles of Carystus, also an early writer, compared, for ability, with Hippocrates himself. He was the first to point to the distinction between pneumonia and pleurisy; he was the ablest anatomist of his age, and the author of numerous works; among which was a treatise on Hygiene, and another on Gymnastics as applied to the treatment of disease. About the same time also, flourished Petronas, a sort of homeopath, who, according to Celsus, treated fevers by overloading the sick with clothing, in order to increase their heat and thirst. Praxagoras, a contemporary of Aristotle, appears to have been among the first to allude to the pulse, a circumstance, however, also mentioned by Aristotle himself, though not as furnishing any useful indications in the treatment of disease. Plistonicus, a pupil of Praxagoras, may also have contributed somewhat tó the opinions promulgated in the Hippocratic writings, particularly in reference to the humors; to the study of which he and his disciples were more than