The author sets out to locate Bion's model of the mind within the developmental history of psychoanalysis, from Freud to Klein to Bion, using biographical material and clinical case examples, to illustrate Bion's concepts of container/contained, his understanding and use of projective identification, his extension of the use of the countertransference, and his differentiation between the psychotic and non-psychotic aspects of the mind. Links, and attacks against linking are discussed, as well as Bion's thoughts about learning versus knowing, being versus becoming and his emphasis on the essential importance of the development of the capacity to think.