It is one of the outstanding disgraces of medicine that for centuries it practically neglected the primordial requisites of organic existence and failed to supply these in any adequate manner to either the well or the sick. At least from the time of Galen it classed these as nonnaturals, while classing its drugs as naturals, and tended to place all its reliance in its alleged naturals. Yet it is the larger, universal, material substances and influences that promote and conserve life. Living is subject to these larger influences and no system of caring for the well or the sick that ignores them can possibly be successful. Reserving for a future chapter the subject of food, in this chapter we shall briefly discuss a few of the primordial requisites of organic existence under separate headings, beginning with