[9] Address delivered at the Annual Commencement of the Medical Department of the University of Chicago, (Rush Medical College), June 13, 1906. History in general is but a record of the succession of great events or epochs which have moulded the world's affairs. That which is of the greatest import in the life of the individual may count for little in the lives of his contemporaries, and yet it must be said that in the events of to-day there has occurred a great epoch in the life of each of you, presumably the most important as yet in your personal records. This day is then in your personal histories one of the greatest importance. It is desirable, therefore, that your lives be so moulded and influenced by it that you may long hence look back to it and recall its significance. I do not know what advice I can give you which will be more fruitful of results, than that among your studies you include that of the lives of the great men who have moulded destiny and made the world's history. Their lives were modified by little things, as have been and will be yours, and yet out of small matters grew for them and for us some of the most far reaching effects. Select the really great men of whom you best happen to know and analyze their characters that you may appreciate how they have become great; while if they have, as all great men have, traits of smallness, study even wherein they are small, and how such faults may be avoided. History runs as does a fairly steady stream, save that every now and then some event abruptly diverts its course or influences its current. It has been so, for instance, with the history of medicine. For the first sixteen hundred years of the Christian era men engaged in the crude practices of our profession, utterly ignorant of the course of the blood, as well as of its purposes. Then appeared upon the scene a man who did his own thinking, who was willing to free himself from the shackles of the past, to observe nature and to reason therefrom. In this way came suddenly upon the world, as it were, an appreciation of the Circulation of the Blood, than which perhaps no event in medical history has been of greater importance or reflected more credit upon its demonstrator. It is my purpose, then, to-day to try to tell you, in a semipopular way, how William Harvey came to make this great discovery, as well as to give you some idea of the difficulties under which he worked, and of the men and influences that surrounded him, believing that rather than spend a half hour in humorous platitudes which may provoke a smile, but which are quickly forgotten, it is much better to try to implant something which may linger a while in your memories, and sufficiently impress you with the value of observation and inductive reasoning, since if you become thus fully impressed you will be spared in the future many sad errors of speech and even of thought.