John Webster, one of the world's leading systematic theologians, published extensively on the nature and practice of Christian theology. This work marked a turning point in Webster's theological development and is his most substantial statement on the task of theology. It shows why theology matters and why its pursuit is a demanding but exhilarating venture. Previously unavailable in book form, this magisterial statement, now edited and critically introduced for the first time, presents Webster's legendary lectures to a wider readership. It contains an extensive introductory essay by Ivor Davidson.