This introduction discusses traditional meanings of the following concepts: health, sickness, disease, suffering, and healing. The point is made that “disease” is an abstract phenomenon, albeit one that is critically important to the contemporary practice of medicine. Unfortunately, the term disease has often come to occupy the center of physicians’ preoccupations. Currently, health is considered in a negative sense, as an “absence of disease.” This chapter proposes a new and bold definition of sickness, one that revolves around the notion of function. This opens up possibilities for the goals of physicians and for medical education to be truly person centered.