""In this book is presented a theory of interpersonal relations and group functioning. The major motivation that governed this effort was a desire to give cumulative treatment to a discussion of some persistent problems in social psychology and to answer for ourselves the question: how do the data of the field look when they are arranged by their relevance to a conceptual structure that begins with relatively simple assumptions and adds further ones only as they become necessary? If it is not entirely idiosyncratic, any success along these lines might be expected to be useful both as a guide to research and in contributing some order and simplification to an increasingly bewildering congeries of fact." (p. 1, Thibaut & Kelley, 1959)"