According to this view, the etiology or cause of schizophrenia unleashes pathogenetic mechanisms that produce specific pathological entities. Each of these conserved sets of molecular and cellular disturbances in the brain alters the normal circuitry and function of the brain so that the resulting pathophysiology gives rise to distinct components of the clinical syndrome recognized as schizophrenia. The bidirectional arrows indicate the following: (a) understanding pathophysiology and pathogenesis is required for the rational identification of novel molecular targets for improving treatment and secondary prevention, respectively, and (b) proof-of-concept validation of compounds with activity at these targets requires normalization of biomarkers for these processes.