Mescaline produced an inhibitory state accompanied by a schizokenesis or dissociation of systems. This disharmony was also manifested in that the CS appeared to act in the same manner as the US. On this basis a neurodynamic theory of the mechanism of mescaline's actions is postulated: that under mescaline intoxication and in some mental illnesses, a dissociation of the second and first signaling systems and the unconditional reflexes occurs in which each signaling system acts as if it were the same as the more primitive system on which it is based. The secondary signals—words and ideas—come to act like the primary signals of sensations and direct impressions of reality. This theory may help explain certain psychological phenomena, e.g. dreams, hysteria, compulsions, delusions, and hallucinations. While the content of these phenomena depends on the personality of the subject and all the environmental factors that determine this personality, their mechanisms are physiological, regardless of whether one prefers a pathophysiologic or psychogenic etiology. Based on our experimental findings and the work of others, a neurodynamic pathogenesis of the psychological effects of mescaline is described.