An integrated theory of "schizophrenia" is presented, based on properties of axons interconnecting the cerebral cortex: Rapidly-conducting axons are replaced by more slowly-conducting ones. This premise accounts for many features of schizophrenia, at psychological and biological levels. The theory is compatible with the "stress-diathesis" model, the neurodevelopmental hypothesis, and the dopamine theory of psychosis - but incorporates much additional evidence. Two, almost separate bodies of theory are involved, one explaining psychosis in terms of transmitter dopamine, the other accounting for non-psychotic traits in terms of axonal properties. A key question is: "Why are people with the non-psychotic trait abnormalities also prone to episodes of psychosis?" An answer is based on the premise about axonal conduction. Psychosocial causes are accepted, along with genetic ones: Psychosocial causes promote psychosis in predisposed individuals, without contributing to the basic constitution for schizophrenia.