The discovery in the 1970's of endorphins--opiates produced by the body and implicated in a wide range of human behavior from addiction to depression to creativity--has revolutionized neurobiology and shaken up psychology. In this brief but competent account, Levinthal (Psychology/Hofstra) chronicles our understanding of endorphins and their exo-body imitators (opium, heroin, etc.). To place endorphins in context, Levinthal opens with familiar material: the history of opiate use from ancient Greece through the discovery of heroin and beyond, followed by a concise if rather technical account of the evolution of the brain and of our knowledge of its biochemistry. By 1970, he explains, it was clear that specific brain sites existed for the reception of opiate molecules: the biochemical root of opiate addiction. In one of those odd confluences that mark science history, three separate teams of researchers almost simultaneously located those opiate receptors, paving the way for the isolation of the body's own opiates--endorphins--that must exist to fit the receptors. Levinthal covers the serial races for discovery (and consequent public reward), and then explores the ramifications of endorphins. Sifting through a decade's worth of experiments, he shows how endorphins (which are amino-acid peptides) are: analgesic towards physical pain (hence the efficacy of acupuncture) and towards stress; the key to drug addiction, where exo-body opiates usurp endorphins' proper role; and, most startling, associated with much psychological behavior, their presence noted in mother-child bonding and the thrill of music, for instance, and their absence noted in autism, depression, and doubt. Levinthal closes with a brief meditation on endorphins' probable role in the creative processs. Levinthal brings a textbook-writer's sensibility (he's the author of Introduction to Physiological Psychology) to his presentation, touching bases succinctly without communicating the full wonder and most far-flung implications (i.e., religious) of endorphins. Still, in all, a conscientious if uninspired introduction to the subject.