Biological psychiatrists tend to look upon the phenomena of mind and meaning, which are the data of psychoanalysis, as meaningless epiphenomena, and propose reductive explanations of complex mental states, whereas psychoanalysts tend to ignore the proliferation of neurobiological data indicating the importance of constitutional factors in mental illness. Interactive models which confuse biological causes and psychological consequences, or vice-versa, are theoretically unsound. A scientific model hierarchy is proposed, along with some principles for coexistence and collaboration between neurobiology and psychoanalysis. The problem is illustrated with schizophrenia, a condition whose probable biological underpinnings are now generally considered to remove it from the realm of psychoanalysis. Schizophrenia-vulnerable phenotypes consistent with organic findings and clinical observations are hypothesized, and some ideas about their development in the context of early object relations, leading to pathological forms of symbiosis, are elaborated. A neurobiological rationale for the psychoanalytic treatment of schizophrenia is presented, and special problems related to the biological and symbiotic substrate are examined.