I should not have troubled the reader with this very unimportant narrative except for the purpose of explaining the long interval that has elapsed between the delivery of the lectures and their publication. Literary composition I have always found laborious and slow, even in favourable conditions. But the conditions have not been favourable. My anxiety to make the argument easy to read for persons who take little interest in, and have small knowledge of, philosophical controversies did not make it easy to write; while external circumstances were singularly unfavourable to rapid composition. No one who took any part in public affairs between March 1914 and the outbreak of the war, or between the outbreak of the war and the present moment, is likely to regard these months as providing convenient occasion for quiet thought and careful writing. I say this, however, not as an excuse for poor workmanship, but only as an explanation of long delay. It may be desirable to warn the intending reader before he embarks on these lectures, that though the basis of the argument is wide, its conclusion is narrow: and though that conclusion is religious, the discussions leading up to it are secular. I make no dialectical use of the religious sentiment; nor do I attempt any analysis of its essential character. Still less do I deal with any doctrines outside what is called “natural” religion; for to “natural” religion the Gifford Lecturer is expressly confined. But even themes which might well be deemed to fall within these limits are scarcely referred to. For example, God, freedom, and immortality have been treated by at least one eminent writer as the great realities beyond the world of sense. I believe in them all. But I only discuss the first—and that only from a limited point of view. One other caution I must give, though it is hardly necessary. No one, I suppose, is likely to consult this small volume in the hope of finding an historic survey, properly “documented,” of the great theistic controversy. But, if so misguided an individual exists, he is doomed to the severest disappointment. There have been, and will be, Gifford Lecturers well equipped for so great an undertaking; but most assuredly I am not among them. My warm thanks are due to my brother, Mr. Gerald Balfour; my sister, Mrs. Sidgwick, and my brother-in-law, Lord Rayleigh, for the trouble they have taken in reading the proofs, and for the aid they have given me in correcting them. In connection with a passage in the ninth lecture, Sir Oliver Lodge has been good enough to give me an interesting note on “energy,” which appears in its proper place. 4 CARLTON GARDENS _May 24, 1915_. CONTENTS PART I _INTRODUCTORY_ LECTURE I PAGE I. INTRODUCTORY: METAPHYSICS AND THE “PLAIN MAN” 3 II. “INEVITABLE” BELIEFS AND COMMON SENSE 13