This lecture will describe aspects of the art and science of psychopharmacology, with special emphasis on correcting common misconceptions. It will be explained that medications can be used in one of two ways, either symptomatically or disease modifying. Symptomatic agents are like aspirin for a headache or Tylenol for a fever; they improve symptoms short term but do not alter the long-term course of the illness. Almost all psychiatric medications, including antidepressants and antipsychotics, are symptomatic, and have no effect on the long-term diseases that underlie many psychiatric presentations. Disease modifying drugs improve the long-term course of illness, affect the pathogenesis of a disease (not just the biology of its symptoms) and, if very effective, reduce mortality. Only lithium among all psychiatric medications has these effects.   This fact will be explored in the context of the general philosophy of clinical medicine derived from Hippocrates, which has nothing to do with the false concept of “First do no harm”, but rather is based on the view that symptom-oriented treatment is to be discouraged in favor of disease-oriented treatment. Implications of these observations for the use of psychiatric medications in clinical practice will be explored, with special emphasis on the disease-modifying effects of lithium.