First published in 2002. The Library of Philosophy was designed as a contribution to the History of Modern Philosophy under the heads: first of different Schools of Thought-Sensationalist, Realist, Idealist, Intuitivist; secondly of different Subjects-Psychology, Ethics, Aesthetics, Political Philosophy, Theology. This is volume XVI of twenty-two in a series of 20th Century Philosophy focuses on the commonplace book of George Moore. The papers include nine notebooks, written at various times between 1919 and 1953.