Professor Hartshorne's recent book¹ is without doubt one of the most serious and sustained works on so-called process philosophy since the publication of Process and Reality itself. It invites the reader to think out to the depths the foundations of this view without sparing difficulties along the way. Above all, the "method of convenient ignorance"—scientia non habet inimicum nisi ignorantem—is not his, for few contemporary metaphysicians have been so consistently concerned with the relevance to their subject of recent work in the empirical sciences, mathematics, and above all, logic, as he. And few if any have to equal degree combined this interest with unusual sensitiveness to and concern for aesthetic, ethical, social, humane, and religious values. A synoptic vision of a total philosophy is given in this book, with fascinating side views, as it were, leading out into almost all the areas of thought with which philosophers throughout the ages have been concerned.