Very few persons will challenge the truth of the statement that in the United States and Canada there are not many physicians who possess even a slight knowledge concerning the manner in which the science of medicine has attained its present power as an agency for good, or concerning the men who played the chief parts in bringing about this great result. Up to the present time no blame may justly be attached to any individuals or to any educational institutions for this prevailing lack of knowledge, and for two very good reasons, _viz._: first, in a newly settled country, in which the population grows by leaps and bounds through the influx of foreign immigrants, the training of young men for the degree of M.D. must necessarily be almost entirely of a practical character, and consequently the teaching of such a subject as the history of medicine would be quite out of place; and, second, the treatises on this subject which are purchasable by English-speaking physicians are of rather too scientific a character to appeal either to the undergraduate or to the busy practitioner. The first of the reasons named, it may now safely be assumed, is rapidly losing its validity, if indeed it has not already ceased entirely to afford a legitimate excuse for neglecting the study of this branch of medical science. On the other hand, the second reason mentioned is still in force,--so far at least as the present writer knows,--and, if such be the case, it certainly cannot fail to act as a deterrent influence of great potency. Here, then, is my apology for attempting to prepare an account of the history of medicine which shall present the essential facts truthfully and with a sufficient degree of attractiveness to win the continuing interest of the reader; which shall place before him, and especially before those who are just at the threshold of their professional career, word pictures of those physicians of past ages whose lives may safely be taken as models worthy to be copied; and which shall describe, so far as I am able to do this, the methods which they employed to advance the science of medicine, to gain genuine professional success, and to merit the enduring esteem of later generations of physicians. If my efforts prove successful in producing this kind of history it is fair to expect that, in a comparatively short time, those physicians whose interest may have been aroused by the perusal of this less complete and more popular work, will demand something of a more exhaustive character--a book, for example, like the admirable history which Max Neuburger, of Vienna, is now publishing, and of which two volumes have already issued from the press (the first in 1906 and the second in 1911).[1] It is to this work and the excellent history written by the late Dr. Haeser, of Breslau, that I am chiefly indebted for the information supplied in these pages; and I therefore desire to make special mention here of this indebtedness.