In Freud's work the analyst finds a probably unique and in many respects inimitable blending of clinical observation, concept and hypothesis formation, technical principles, and the use of analytic insight in neighboring fields of knowledge. All these constituent aspects of psychoanalysis appear to be, in his mind and work, in a highly integrated and dynamic state of equilibrium. Among his followers, not all of whom partook of the universality of his interests and the style of his thinking, a certain degree of specialization, of division of labor, became the rule rather than the exception. This process of differentiation, which to some extent followed the patterns known from other scientific fields, seems natural enough and may be productive, though only as long as the common ground any