This work contains the Boyle Lectures of 1920. The reader will not find the outlines of a system of philosophy or theology; and he will probably be as conscious as their author that many questions are raised which are not fully discussed, while others which might have been relevant are passed over altogether. The author's main object in these lectures has been to suggest that Christian doctrine rests upon a few simple affirmations of a philosophical character, and to indicate a line of thought which seems to lead to the conclusion that these affirmations are rational.