The bland title to psychiatrist/neurologist Restak's latest (The Brain Has a Mind of Its Own, 1991, etc.) refers to the fascinating subject of drugs and the brain. In the last few decades, investigators have discovered an increasing number of chemicals that grease the brain's circuits: the neurotransmitters that cross the synapse between nerve cells and bind to receptors on the neighboring nerve cell membrane. The receptors themselves have been elusive, but they, too, are yielding to modern technology. All thought, emotion, and behavior are thought to stem from the complex interactions of transmitters with receptors: complex because a transmitter may bind to more than one receptor and nerve cells may secrete several receptors--phenomena that go far to explain the fine shading of human behavior. Here, Restak begins with the hallucinogens and the work of the German investigator Louis Lewin, who collected peyote buttons in Mexico and isolated mescaline. In the 1940's came the discovery of LSD 25 by Albert Hoffman, in Switzerland, who later isolated psilocybin, the magic mushroom's ingredient. There were hints that the drugs were related to naturally occurring brain chemicals, but how they worked was unclear (and still is). Much serendipity attended the early research: The use of lithium to treat manic- depression might never have come about had it not been for an Australian psychiatrist's use of lithium to dissolve uric acid from manic-depressive patients in order to inject it into guinea pigs. Today's roster of psychoactive drugs include the strong tranquilizers, the antidepressants, stimulants, and opiates- -effective because they bind to specific receptors as ``agonists,'' or block the binding of the natural chemical as ``antagonists.'' Restak is very good on origins and etymologies--and highly speculative about the future. Someday, he foresees, we may be able to sculpt the precise structure for fine-tuning cures of mental illness and even effect permanent changes to ``improve'' personality. Someday in the Brave New World? More tolerable is Restak's earlier conclusion that ``the drugs developed within any society reflect and amplify the ideals and goals of that society.''