To know accurately the anatomical changes that take place in disease is of importance both for diagnosis and for treatment. The man who created the science, who taught us to think anatomically of disease, was Morgagni, whose "De sedibus et causis morborum per anatomen indagatis"(4) is one of the great books in our literature. During the seventeenth century, the practice of making post-mortem examinations had extended greatly, and in the "Sepulchretum anatomicum" of Bonetus (1679), these scattered fragments are collected.(5) But the work of Morgagni is of a different type, for in it are the clinical and anatomical observations of an able physician during a long and active life. The work had an interesting origin. A young friend interested in science and in medicine was fond of discoursing with Morgagni about his preceptors, particularly Valsalva and Albertini, and sometimes the young man inquired about Morgagni's own observations and thoughts. Yielding to a strong wish, Morgagni consented to write his young friend familiar letters describing his experiences. I am sorry that Morgagni does not mention the name of the man to whom we are so much indebted, and who, he states, was so pleased with the letters that he continually solicited him to send more and more "till he drew me on so far as the seventieth; . . . when I begged them of him in order to revise their contents; he did not return them, till he had made me solemnly promise, that I would not abridge any part thereof" (Preface). (4) Venice, 1761. (5) Boerhaave remarked that if a man wished to deserve or get a medical degree from ONE medical author let it be this. (James Atkinson: Medical Bibliography, 1834, 268.)