On the occasion of a visit to Abdera, in the northern part of Thrace, Hippocrates was requested to examine into the mental condition of the philosopher Democritus, who was thought by his narrow-minded countrymen to be insane. Hippocrates found him deeply engrossed in the study of natural philosophy and asked him what he was doing. Democritus replied that he was investigating the foolishness of men. Whereupon Hippocrates reported that he considered Democritus the wisest of men. (Pagel.) No better evidence of the true greatness of a man can be furnished than that which is afforded by the praise of his contemporaries in the same rank or walk of life; and when the appreciation comes from such men as Plato and Aristotle, it constitutes an absolute guarantee that it is well and honestly earned. To Hippocrates belongs the singular honor of having won unstinted praise from both of these great philosophers, Aristotle giving him the title of “Hippocrates the Great,” and Plato comparing him to those famous sculptors, Polyclytus and Phidias. His writings and those of the members of his family who were associated with him in the work of promoting a knowledge of medicine were most carefully preserved by his successors. When the Ptolemies began to establish libraries at Alexandria, Egypt (285 B. C.), and manifested a decided readiness to purchase the works of the most celebrated authors, copies of the Hippocratic writings were among those which found their way to that city. This eagerness on the part of the Kings of Egypt to purchase books or manuscripts stimulated unscrupulous persons to attribute to celebrated authors not a few of these works which they offered for sale. The librarians, whose duty it was to guard against such frauds, were not sufficiently well informed to prevent them; and thus there were accepted, as genuine productions, a few books which could not possibly have been written by those to whom they were attributed. The collection of Hippocratic writings did not escape this fate, and the evil was also further aggravated by the fact that copyists and incompetent editors made all sorts of emendations and additions on their own responsibility. Thus, it is not surprising that a collection which originally contained only the writings of Hippocrates and his immediate family, should in course of time have become expanded, not only by such alterations as have just been described, but also by the addition of entire works that had been written by others. At the beginning of the third century B. C., the Ptolemies appointed a committee of learned men in Alexandria to examine carefully the treatises reputed to be the work of Hippocrates and to make a collection of those which appeared to them to be genuine. They performed this task to the best of their ability, but the result showed that they lacked the necessary critical powers; and consequently during the past 2000 years repeated attempts have been