Wallerstein examines what holds psychoanalysts together as common adherents of a shared science and profession. He describes what the diverse perspectives have in common and what differentiates them, all together, from all the other theories of mental life. The common ground rests in the shared clinical enterprise in consulting rooms where therapists relate comparably to the immediacy of the transference-counter-transference interplay with their patients. He applies these conceptions to clinical material of three of the major perspectives in the field: the ego psychological, the Kleinian, and the object relational.