This work, composed originally for a lay audience and for popular consumption, will be to the aspiring medical student and the hardworking practitioner a lift into the blue, an inspiring vista or "Pisgah-sight" of the evolution of medicine, a realization of what devotion, perseverance, valor and ability on the part of physicians have contributed to this progress, and of the creditable part which our profession has played in the general development of science. The manuscript of Sir William Osler's lectures on the "Evolution of Modern Medicine," delivered at Yale University in April, 1913, on the Silliman Foundation, was immediately turned in to the Yale University Press for publication. Duly set in type, proofs in galley form had been submitted to him and despite countless interruptions he had already corrected and revised a number of the galleys when the great war came. But with the war on, he threw himself with energy and devotion into the military and public duties which devolved upon him and so never completed his proof-reading and intended alterations. The careful corrections which Sir William made in the earlier galleys show that the lectures were dictated..