based in the phenomena of the analytic encounter, revealed both correspondences and expansions of core ideas from both Sigmund Freud and Melanie Klein. At one point, he attempted to understand thoughts and thinking from an 'algebraic', 'geometric' and 'mathematised' point of view, believing there to be too little precision in the existing vocabulary, a process culminating in "The Grid". Later he abandoned the complex, abstract applications of mathematics, and the Grid, and developed a more intuitive approach, epitomised in Attention and Interpretation (1970). In 1968, Bion moved to Los Angeles, California, where he remained until 1977. During those years he mentored a number of psychoanalysts interested in Kleinian approaches, including James Gooch (psychoanalyst) and other founding members of the Psychoanalytic Center of California. Shortly before his death, he returned to Oxfordshire. Reception and stature Bion left a reputation which has grown steadily both in Britain and internationally. Some commentators consider that his writings are often gnomic and irritating, but never fail to stimulate. He defies categorisation as a follower of Klein or of Freud. While Bion is most well known outside of the psychoanalytic community for his work on group dynamics, the psychoanalytic conversation that explores his work is mainly concerned with his theory of thinking, and his model of the development of a capacity for thought. Wilfred Bion was a potent and original contributor to psychoanalysis. He was one of the first to analyse patients in psychotic states using an unmodified analytic technique; he extended existing theories of projective processes and developed new conceptual tools. The degree of collaboration between Hanna Segal, Wilfred Bion and Herbert Rosenfeld in their work with psychotic patients during the late 1950s, and their discussions with Melanie Klein at the time, means that it is not always possible to distinguish their exact individual contributions to the developing theory of splitting, projective identification, unconscious phantasy and the use of countertransference. As Donald Meltzer (1979, 1981), Denis Carpy (1989, p. 287), and Michael Feldman (2009, pp. 33, 42) have pointed out, these three pioneering analysts not only sustained Klein's clinical and theoretical approach, but through an extension of the concept of projective identification and countertransference they deepened and expanded it. In Bion's clinical work and supervision the goal remains insightful understanding of psychic reality through a disciplined experiencing of the transference–countertransference, in a way that promotes the growth of the whole personality. 'Bion's ideas are highly