 1886–1912. Santayana received his Ph.D. from Harvard in 1889 and became a faculty member at Harvard University (1889–1912) and eventually a central figure in the era now called Classical American Philosophy. He was a highly respected and popular teacher, and his students included poets (Conrad Aiken, T. S. Eliot, Robert Frost, Wallace Stevens), journalists and writers (Walter Lippmann, Max Eastman, Van Wyck Brooks), professors (Samuel Eliot Morison, Harry Austryn Wolfson), a Supreme Court Justice (Felix Frankfurter), many diplomats (including his friend Bronson Cutting), and a university president (James B. Conant). He retired from Harvard in 1912 at the age of forty-eight and lived the remainder of his life in England and Europe, never returning to the U.S. and rejecting academic posts offered at a number of universities, including Harvard, Columbia, and Cambridge.