The most thorough and wide-ranging discussion for lay readers about the interplay of the physical and emotional elements of depression and manic-depression. The popular and controversial antidepressant Prozac has made serotonin and other mood-related neurotransmitters in the brain familiar to many. But Whybrow (coauthor, The Hibernation Response, 1988), chairman of psychiatry at the University of Pennsylvania, shows how these messenger chemicals fit into the larger structure of the brain, and in particular of the limbic alliance, which includes the amygdala and the thalamus, and which governs our emotions. Whybrow defines mood disorders as a disruption of the limbic alliance's homeostasis--its self-regulating power--which in turn disrupts three areas of activity: thinking (such as memory), feeling (which becomes dominated by negativity), and ``housekeeping'' (such as sleeping and eating patterns). Sometimes the highly detailed scientific discussion becomes a little convoluted, a little redundant, and a little too full of gee-whizzing about the wonders of the human brain. But overall his presentation is illuminating, and the case histories demonstrate his sensitivity and skill as a clinician. In particular, the story of John Moorehead, a Jesuit academic with a generally optimistic and intellectually curious nature who suddenly plunged into a profound depression, illustrates the tortured and complex nature of manic-depression. His case also demonstrates one of Whybrow's most emphatic points: that experence, especially human attachment, is as important as biology in causing mood disorders. Thus, while Moorehead had a genetic predisposition to his illness, it flared up only after the breakup of a profound friendship. Whybrow therefore stresses that however effective drugs such as Prozac may be, they must be combined with psychotherapy. Because of its emphasis on complicated neurobiology, this is not the place to begin learning about mood disorders. But for those already familiar with the subject, Whybrow's presentation offers a deeper understanding of, along with a humane and wise approach to, these very troubling illnesses.