The book is consists of lectures by Reginald O. Kapp, known as Riddle Memorial Lectures. As the title suggests, the lectures are partly concerned with conflict between science and religion. But their main theme is better indicated by the sub-title 'The Dual nature of Reality'. The author's aim is to present the case for a dualistic philosophy of nature and against a monistic one. This issue, he argues, is of enormous importance for the philosophy of science, but is less important for theology than is commonly thought. "I doubt, indeed, whether monism is bad religion. But I am sure that it is bad science."