Based on the Silliman Lectures delivered at Yale in 1913, this book remained unfinished at Osler's death. He requested in his will that it and his other unfinished works not be published. However, it was prepared for publication by Harvey Cushing, Archibald Malloch and others. Garrison said it is one of the most interesting short histories of medicine, written in Osler's charming style, an excellent book to begin the study of medical history.