The chief data for Vesalius’s biography are to be found in his own writings, in the archives of the Universities in which he taught, and in the controversial literature of the period. Extensive as are these sources they leave much to be desired. A vast mass of Vesalian literature was printed, chiefly in the Latin language, during the seventeenth and eighteenth centuries. Much of it is based on insufficient evidence or on national prejudice. The Germans, the French, the Dutch and the Italians have all taken a turn at it. In modern times the monumental work of Roth, _Andreas Vesalius Bruxellensis_, Berlin, 1892, has served to epitomize this literature and to make clear many points which formerly were not understood. I have taken Roth’s book as a basis for this monograph, without using the voluminous references which are found in the work of this thorough historian. The man who overthrew the authority of Galen; revolutionized the teaching of the structure of the human body; started anatomical, physiological, and surgical investigation in the right channels; first correctly illustrated his dissections; destroyed ancient dogmas, and made many new discoveries—this man, Andreas Vesalius of Brussels, deserves the name which Morley has given him, “the Luther of Anatomy.” At long intervals a bright particular star appears in the intellectual horizon, endowed with genius of such a superlative order as seemingly to comprise within itself the whole domain of an entire science. These men do not belong to any particular epoch in the development of the human mind. They are the eternal symbols of progress, and their history is the history of the science which they profess. Such men were Bacon, Galileo, Descartes, Newton, Lavoisier, and Bichat; and such also was Andreas Vesalius the anatomist. Young, enthusiastic, courageous and diligent, Vesalius dared to contradict the authority of Galen, corrected the anatomical mistakes of thirteen centuries and before his thirtieth year published the most accurate, complete, and best illustrated treatise on anatomy that the world had ever seen. His industry, the success which crowned his efforts, the jealousies which his discoveries aroused in the breasts of his contemporaries, the honors which were conferred upon him by Charles the Fifth and Philip the Second, his pilgrimage to the Holy Land, and his tragic death—these are events which deserve to be chronicled by an abler pen than mine.