pubOne.info thank you for your continued support and wish to present you this new edition. The substance of this little book was delivered in the form of two lectures given at the invitation of the Hibbert Trustees in Manchester, Liverpool, Leeds and Birmingham during March and April, 1922. On revising the spoken word for the press I have made certain rearrangements which seemed to be required in committing the lectures to the printed form. The first section is wholly new and may be considered as a short introduction to the main theme. Such an introduction is, I think, needed, but the time at my disposal did not allow of its inclusion in the oral delivery of the lectures.