The first revolution was the redefmiton of the mad as sick people needing treatment; the second, Freud's theories of traumatic cause. The third--what Freud himself always hoped for--is, according to Dr. Fieve of the New York Psychiatric Institute, chemotherapy, the re-redefinition of many mental illnesses as metabolic disorders and their treatment with drugs. This book limits itself to one kind of chemotherapy, the best-defined and most incontrovertible to date (though no one knows how or why it works): the treatment of manic-depression with a naturally occurring salt called lithium carbonate. This is a popular book--as witness its animated style, its dramatization through case histories, and its anecdotes of famous manic-depressives from Abraham Lincoln to Thomas Eagleton--but it is by no means an irresponsible or oversimplified one. Fieve is honest, if at times digressive, on the complexities of such questions as whether artists' manicdepressive cycles are essential to their creativity, whether psychiatrists have any business intervening in politics, and whether psychotherapy works. His answer is always moderate: if artists' or anyone's moodswings aren't too harmful or painful, they should go untreated, since mild mania is often productive (he cites a number of successful business men). Fieve seems conflicted between his advocacy and his reasonableness: once a condition is defined as a ""disorder"" he is led to speak of ""the benefits of mental illness"" and conversely--and ominously--to confuse a desirable ""normal"" with what is merely average. Still an interesting if padded book--informative on the etiology and treatment of manic-depression and its relation to alcoholism and drug use, though ultimately failing to make a strong case for its biochemical or genetic causes.