Jose Delgado is one of the pioneers in the field of electrical stimulation of the brain ESB. It is he who has been depicted stopping a charging bull dead in its tracks by pushing a button to send an electrical signal to a certain part of the bull's brain. But in this study Delgado reveals himself not as a showman or wonder worker but a profoundly serious scientist concerned with the neglect of this and other areas of cerebral research. His experiments have shown unambiguously that there are specific areas of the brain which are involved in ""starting,"" ""organizing,"" or ""performing"" activities of varying degrees of sophistication: Patients with electrodes implanted deep inside their brain may become more communicative and friendly, or more hostile and aggressive. They may involuntarily flex their fingers, feel pain or pleasure, or have a sudden experience of deja vu. The implications of this work, the philosophical, moral, and ethical questions it raises, are very seriously addressed in this group of essays (which grew out of the Salmon Memorial Lectures). Delgado has clear and precise things to say about the meaning of mind, the essential importance of sensory inputs (there is no mind without it: the newborn is mindless), and very positive feelings about the potential use such techniques may have therapeutically as well as in the possibility of man's controlling his destiny. The book stands as a complement to Perry London's Behavior Control (p. 762). While that book was a good survey of all current methods of altering mental states such as psychotherapy, drugs, surgery and ESB, Delgado's is a profound discussion of the one field in which he is the authoritative source.