As far as Hippocrates attempts to ex plain the causes of disease, he refers much to the humours of the body, par ticularly to the blood and the bile. lie treats also of the effects of sleep, watch ings, exercise, and rest, and all the benefit or mischief we may receive from them ; of all the causes of diseases, however, mentioned by Hippocrates, the most ge neral are diet and air. On the subject of diet be has composed several books, and in the choice of this he was exactly care ful ; and the more so, as his practice turned almost wholly upon it. He also considered the air very much ; he ex. amined what winds blew ordinarily or ex traordinarily; he considered the irregu larity of the seasons, the rising and set ting of the stars, or the time of certain constellations,; also the time of the sol stices, and of the equinoxes; those days, in his opinion, producing great alterations in certain distempers ; he does not, how ever. pretend to explain how, from these causes, that variety of diseases arises which is daily to be observed. All that can be gathered from him with regard to this is, that the different causes above mentioned, when applied to the different parts of the body, produce a great variety of disorders; some of these he accounted mortal, others dangerous. and the rest easily curable, according to the cause from whence they spring, and the parts on which they fall : in several places, also, he distinguishes diseases from the time ef their duration, into acute or short, and chronical or long. He likewise distin guishes diseases by the particular places where they prevail, whether ordinary or extraordinary. The first, that is, those that are frequent and familiar to certain places, he called endemic diseases ; and the latter, which ravaged extraordinarily, sometimes in one place, sometimes in an other, which seized great numbers at cer tain times, he called epidemic, that is popular diseases; and of this kind the most terrible is the plague. He likewise mentions a third kind, the opposite of the former ; and these he calls sporadic, or straggling diseases : these last include all the different sorts of distempers which invade any one season, which are some times of one sort, and sometimes of an other. He distinguished between those diseases which are hereditary, or born with us, and those which are contracted afterwards ; and likewise between those of a kindly, and such as are of a malig nant nature ; the former of which are easily and frequently cured, while the lat ter give physicians a great deal of trou ble, and are seldom overcome by all their Care.
A foundation for the theory ;ad prac tice of medicine, being thus laid, the science was pursued with great avidity by Praxagorss, who nevertheless ventured, in some respects, to oppose the practice of Hippocrates, and by Erasistratus and Herophilus, of whom the last, as a dis ciple of Praxagoras, inclined rather to the Praxagorean than the Hippocratic school. Erasistratus, however, acquired a higher fame, though a more steady ad herent to the older and Hippocratic doc trines, and to him we are indebted for the first regular indications of the pulse.
About this period the profession of me dicine began to be divided into the three branches of dietetic, pharmaceutic, and chirurgic or those who pretended to cure by regimen alone, disregarding, and even despising, pharmacy ; those who undertook to cure chiefly by pharmaceu tic preparations (of which number was Erasistratus himself) and those who devoted their whole time and attention to the chirurgical department of the medical art.
The next division of medical practi tioners was into that of dogmatists and empyrics ; the latter having commenced with Serapion of Alexandria, about the year 287 before Christ, who, according to Galen, retained the mode of practice of Hippocrates, but pretended to despise his mode of reasoning In reality, this sect, to which Serapion belonged,and of which, if not the founder, he was a very zealous supporer in its e.irliest infancy, depend
c1 upon thew ow a personal experience alone, whether progressive or fortuitous. On the contrary, the dogmatists affirmed that there is a necessity for knowing the latent as well as the evident causes of diseases, and that physicians ought to understand the natural actions and func tions of the human and conse quently its internal organs.
The physicians of chief fame, who flou rished subsequently to this division, were Asclepiades, who opposed the Hippocra tic theory of natural power and sympathy or attraction, by engrafting upon medicine the physical principles of the Epicurean philosophy: Themison, the founder of the methodic sect, whose doctrines evinced equal hostility to the dogmatists and em pyrics, and divided diseases into the two classes of hypertonic and atonic, a division which in various modifications has de scended to the present day ; Thessalus, contemporary with Nero, a man of some merit, but of inordinate vanity ; and Cel sus, deservedly denominated the Latin Hippocrates, whose work is equally valu able for the purity of its language, and the knowledge it communicates of the state of medicine at the time he wrote.
About the year after Christ 131, in the reign of Adrian, appeared the celebrated Galen, whose name makes so conspicuous an appearance in the history of physic. Practitioners were at this time divided in to the three sections of methodists, dog matists, and empyrics. Galen inclined to the second party, but with a true eclectic spirit undertook to combine with its doc trine whatever existed of real worth in the two adverse systems ; and hence to reform and give a finish to the science of medicine beyond what it had ever pos sessed before For the most part he was a follower of Hippocrates, whose name he revered, and whose opinions he comment ed upon ; asserting in the course of his comments that he never been tho roughly understood before. Like Hippo. crates, he denominated the vital principle nature ; like him he admitted the exist ence of four distinct humours, from the predominancy,or deficiency,or dispropor tion of which, originates the different tem. persments of the animal frame, and the varieties in the different diseases to which it is subject: these humoursare,the blood, phlegm, yellow and black bile. He like wise established three distinct kinds of auras, gases, or spirits, a natural, a vital, and an animal, which he regarded as so many instruments to distinct faculties; referring the seat and action of the first chiefly to the liver, of the second to the heart, of the third to the brain. His au thority, in spite of all the fancies which are interwoven into his system, continued to prevail till the overthrow of the Roman empire, and learning and the arts were transferred to the eastern empire : under the auspices of which, however, the sci ence of medicine does not appear to have made any progress; the Saracenic phy. siciant, totally neglecting the study of anatomy, and every other auxiliary pur suit, and merely adding to the Ilateria Medica a variety of plants, whose names we now seldom hear of, and whose phar maceutic virtues have long been despised and forgotten.