That seems a simple enough proposition nowadays, but it was at once revolutionary and inspiring in the day of its original enunciation some forty years ago. The man who had made the discovery was a young German physician, professor in the University of Freiburg, by name Rudolph Virchow. The discovery made him famous, and from that day to this the name of Virchow has held somewhat the same position in the world of pathology that the name of Pasteur occupied in the realm of bacteriology. Virchow was called presently to a professorship in the University of Berlin. In connection with this chair he established his famous Institute of Pathology, which has been the Mecca of all students of pathology ever since. He did a host of other notable things as well, among others, entering the field of politics, and becoming a recognized leader there no less than in science. Indeed, it seemed during the later decades of his life as if one encountered Virchow in whatever direction one turned in Berlin, and one feels that it was not without reason that his compatriots spoke of him as "the man who knows everything." To the end he retained all the alertness of intellect and the energy of body that had made him what he was. One found him at an early hour in the morning attending to the routine of his hospital duties, his lectures, and clinical demonstrations. These finished, he rushed off, perhaps to his parliamentary duties; thence to a meeting of the Academy of Sciences, or to preside at the Academy of Medicine or at some other scientific gathering. And in intervals of these diversified pursuits he was besieged ever by a host of private callers, who sought his opinion, his advice, his influence in some matter of practical politics, of statecraft, or of science, or who, perhaps, had merely come the length of the continent that they might grasp the hand of the "father of pathology."