In addition to his teaching duties at the University, Lewis began to publish books. His first major work, The Pilgrim's Regress (1933), was about his own spiritual journey to Christian faith. Other works followed that won him acclaim not only as a writer of books on religious subjects, but also as a writer of academic works and popular novels. The Allegory of Love (1936), which is still considered a masterpiece today, was a history of love literature from the early Middle Ages to Shakespeare's time; Out of the Silent Planet (1938) was the first of a trilogy of science fiction novels, the hero of which is loosely modeled on Lewis's friend J.R.R. Tolkien, author of the children's classic The Hobbit.
