Henry Sidgwick, the English philosopher and educator, was born in Yorkshire and attended Rugby and Trinity College, Cambridge. After a brilliant undergraduate career, he was appointed a fellow at Trinity in 1859. He had already begun to have religious doubts, and in the years following 1860 he studied Hebrew and Arabic intensively, hoping to resolve these doubts through historical research. At the same time Sidgwick was teaching philosophy, and he had for many years been a leading member of the small group that met for philosophical discussions with John Grote. Gradually he came to think that if answers to his religious questions were to be found at all, they would be found through philosophy—but he never fully quieted his doubts. In 1869 he resigned his fellowship because he felt he could no longer honestly subscribe to the Thirty-nine Articles, as fellows were required to do. His...