Summary It is thought that a "neurointellectual" system exists and that its behavior is influenced by the same physiological and pathological processes as the neuromuscular, neurosensory and other systems. One of these processes, that of repetitive or fixed neural action, has been studied in its relation to both neurointellectual and neuromuscular function. Many different clinical symptoms of various types are the result of such neural action. In the "psychological" sphere, these symptoms appear as obsessions and compulsions. The neural basis of obsessive and compulsive states is illustrated and discussed. It is believed that such a concept does not conflict with the theories of the "psychological" origin of such symptoms under other circumstances, but rather that it adds to our understanding of the physiological structure and function of the thoughts and feelings which ignite these "psychological" disturbances. In demonstrating how an intricate symptom such as an obsession may be viewed as a function of a neural unit, form and body is given to an entity which has existed clinically as a reality, but physiologically only as an abstraction.