John Macmurray (1891-1976) characterizes the ideas in his Gifford lectures in this way: ‘The simplest expression that I can find for the thesis I have tried to maintain is this: All meaningful knowledge is for the sake of action, and all meaningful action for the sake of friendship’ (SA, p. 15). Underlying this quotation are two key principles; the first is that the self is defined by action at least as much as by thought and the second is that the development of the self requires dynamic relation with other selves. Consequently Macmurray’s most significant contribution to philosophy is a definition of the person that shifts the focus from the isolated thought of the individual to action, which, in turn, leads to an analysis of the ethical relations of persons. At the time that Macmurray is promoting emphasis on the whole person and highlighting the vital importance of positive relationships, these are original and striking ideas. As a result Macmurray’s ideas are proving to have contemporary relevance in the fields of philosophy, psychology, mental health, education, sociology, politics, theology and feminist theology. In addition, while this book represents the first full-scale analysis and critical appraisal of his work, the recently increased interest in Macmurray’s thought has meant that a number of his books have been reissued, a reader has been published (Conford, 1996) and some of his articles have been collected in an anthology (McIntosh, 2004).