Medical historians of the future may look back on the last seventy-five years as a period when accretions of data regarding the mechanisms of many diseases led their excited but often naive devotees on an intellectual bender. Misunderstanding of the whole process of such disorders as infection came about largely through neglect of careful consideration of the host. This neglect, of course, was not confined just to recent times, and in the charming group of essays entitled "The Pedigree of Disease" Jonathan Hutchinson long ago emphasized the person in his striking discourse on disposition, temperament, and diathesis. In fact, these sound concepts constituted the great bulk of what our medical forefathers understood about treating the sick. It should be emphasized again and again that they treated patients wonderfully well, while we treat the disease, well enough but often to the considerable and unhappy neglect of the sick man or woman.