CASES In 1931, a third-year Harvard medical student saw a cluster of small red dots on his forearm and knew without a shadow of a doubt that he would be dead within six months. In 1942, an obscure medical journal published the student's diary posthumously, for he did indeed die of the disease he had diagnosed in himself, subacute bacterial endocarditis, an infection of the heart valves that was uniformly fatal before the advent of antibiotics. The Harvard professor who submitted the diary for publication said in a brief, sharp introduction that as far as he was concerned, doctors were...