The literature of medicine has fully kept pace in volume with the progress of the art itself, and its quality has steadily improved. To this the great tomes of that gigantic work, the "Index-Catalogue of the Library of the Surgeon-General's Office, United States Army," bear solid testimony. It is a consolidated catalogue, by subjects and by authors' names, of practically every medical book published throughout the world and of every article in the periodical literature of medicine. For its existence the world is indebted to Dr. John S. Billings, formerly a surgeon of high rank in the army and now the director of the New York Public Library, and for its continued existence to the United States Government, and it is to be hoped that Congress will never cease to provide adequately for its continued publication. Its completeness and its accuracy long ago led to its being prized everywhere. There are some problems of which medicine has hardly yet entered upon the solution. Prominent among them is that of cancer. Little as we now know of the real nature of that disease, we know quite as much of it as we knew but a few years ago concerning other diseases equally destructive and far more prevalent, which, however, we have now practically mastered. Who can say that we shall not triumph over cancer while the Twentieth Century is still young? Our final triumph is indubitable. The strongest individuality in the medicine of the Nineteenth Century was without doubt that of Rudolf Ludwig Karl Virchow (commonly written by him simply Rudolf Virchow). Although he took no direct part in any of the striking advances in practice that appeal to the laity, yet he was recognized the world over, among all classes of educated and well-informed persons, as the one beacon light of Nineteenth-Century medicine whose glow had been the steadiest and the most enduring. This is because of the wide range of his learning in matters not pertaining closely to his profession. His professional brethren hold the same view, and this is because he so well controlled himself--checked himself at every turn by the severest application of system--that he continued for more than half a century an anchor to hold medical thought strictly down to fact. This was from no natural lack of volatility, for he was an _Acht-und-vierziger_ (Forty-eighter). In 1846, as a prosector in the University of Berlin, Virchow entered with Reinhardt upon a series of pathological investigations which at once received wide attention. In conjunction with Reinhardt, he founded the _Archiv für pathologische Anatomie und Physiologie und für klinische Medicin_[6] (a periodical familiarly called "Virchow's _Archiv_"), the publication of which was begun in the year 1847. Reinhardt died in 1852, leaving the editorship in the hands of Virchow alone, and he was still its editor up to the time of his death, on September 5, 1902. [Footnote 6: Archives of Pathological Anatomy and Physiology and of Clinical Medicine.]