Because the brain controls the whole body and all mental activities, ESB could possibly become a master control of human behavior by means of man-made plans and instruments. In previous sections we have described methodology for brain stimulation and many effects evoked by ESB. This section will discuss the meaning of these results, the mechanisms involved, the expected limitations, and the problems facing investigators. How physiological or artificial is the electrical activation of neurons? How predictable? Who is responsible for acts performed under ESB—the stimulated subject or the scientist? Which benefits or risks may be expected in the future? Can we modulate perception and expression by electrical means? Can we expect that brain investigation will provide a new conception of the human mind? These and other questions confront the investigator while he is sending radio messages to induce a muscle to contract, a heart to beat faster, or a sensation to be felt. Evaluation of these experiments requires the formulation of appropriate theoretical concepts and the design of working hypotheses.