Psychoanalysis is a profound theory of body and mind. The psychoanalytic description of the mind's connection to the body, particularly through the unconscious, has made it difficult for philosophy and psychoanalysis to embrace. Freud and Lacan argued that this connection is marked by the passion of the 'knowing subject'. Passion in Theory explores what such a characterisation means and how it provides a key to many contemporary theoretical and philosophical concerns. Unlike many previous studies of psychoanalysis, Robyn Ferrell's analysis - of Freud's metapsychology and its development in Lacanian theory - takes the theory of psychoanalysis as the means to understanding the psychoanalytic project itself. Outlining the philosophical possibilities in psychoanalysis, Passion in Theory reveals the shape of an evolving set of concepts that have direct consequences for contemporary philosophy, empirical science and feminism.