At Harvard in the 1880s a student of philosophy had two teachers to choose between. Josiah Royce, the department's idealist, taught that the universe was ultimately one all-knowing mind. William James, a psychologist moving into philosophy, judged a belief by the difference it made to a life. George Santayana studied under both. In 1883 James advised him not to take up philosophy at all; in 1889 he wrote his doctoral dissertation under Royce. In the end he agreed with neither. His position fits in one sentence: everything that exists is matter, the mind changes nothing in it, and yet what the mind imagines — beauty, religion, moral ideals — is the best part of life, as long as nobody mistakes it for a report of fact.
He had reached Boston in 1872, aged eight, knowing no English. His mother, whose first husband had been a Boston merchant, had moved there to raise the children of that marriage; his father, a Spanish diplomat and painter, brought the boy over and returned to Ávila within a few months, for good. Santayana spent the next forty years in and around Boston and kept his Spanish citizenship all his life. A Catholic Spaniard in the capital of New England Protestantism, he saw its conscience from just outside, and Character and Opinion in the United States, his farewell to the country in 1920, is written from that distance.
At Harvard he taught the poets T. S. Eliot and Robert Frost and became a full professor in 1907, but the post never fitted him. As early as 1892 he wrote to a friend that he could be a professor only by accident, never in essence. The next year brought what scholars of his life call a metanoia, a change of heart. His half-sister Susana had married the previous November; that summer his father died in Ávila; in October Warwick Potter, a student and close friend, died. Afterwards he put the imaginative celebration of life ahead of academic duty. He announced his retirement in May 1911 and, although Harvard's president offered him easier terms, left America for good in January 1912, at forty-eight. His mother died less than two weeks later, and her bequest of $10,000 let him live without a post.
His position was already visible in Interpretations of Poetry and Religion (1900), which argued that religion is poetry that has entered into conduct: true as a poem is true, false when read as science. James judged its philosophy rotten. In Scepticism and Animal Faith (1923) Santayana pushed doubt past Descartes until nothing was certain, then found the start of knowledge in an animal's working trust that there is a world around it; in the preface he called himself a materialist, apparently the only one still alive. What he added to materialism was a distinction between existence and essence. Existence belongs to matter and does all the work. Essence — the timeless character of anything a mind can hold, such as a color or the meaning of a word — exists nowhere and causes nothing. Royce had once told him that this separation was the gist of his philosophy; the four books of Realms of Being (1927–1940) later built a system on it.
Readers took the writer more readily than the system. The philosopher John Dewey called The Life of Reason the most adequate contribution America had yet made to moral philosophy, Emerson excepted, but it was a novel that made Santayana famous. The Last Puritan was a Book-of-the-Month Club bestseller in 1936, the year he appeared on the cover of Time. The later philosophy found few professional readers, and its revival has come slowly, through the MIT Press critical edition of his works and a small society of scholars. What draws them is what made him hard to place: a naturalism that explains religion without dismissing it.
When war came in 1939, Swiss officials refused him a long-term visa, and he stayed in Italy, where he was already living. In October 1941 he moved into a nursing home in Rome run by the Blue Sisters of the Little Company of Mary, a nursing order of Catholic nuns, largely Irish, and lived there in a single room until his death. After the war American writers came to see him, among them the critic Edmund Wilson and the poet Robert Lowell. He died of stomach cancer on 26 September 1952. He had asked to be buried in unconsecrated ground; the Spanish consulate would not allow it and placed him instead in the tomb it kept for Spaniards in Rome's Campo Verano cemetery.