The book brings together a series of lectures that Ronald Knox delivered to Catholic students at the University of Oxford. With extraordinary intellectual acuity and a subtle irony infused with British humor, the author addresses some of the most decisive questions of the Christian faith. Far from presenting a formal defense of Catholicism, Knox engages with the doubts, objections, and concerns of the people of his time, showing how faith responds to the deepest questions of human reason and the human heart.

Throughout its pages, the author reflects on the knowledge of God, the nature of faith, the meaning of miracles, the divinity of Christ, the distinctive marks of the Church, the reality of sin, Christian marriage, and the resurrection of the dead, among other fundamental themes. Knox combines doctrinal rigor with remarkable clarity in the presentation of his arguments. His examples, observations, and reflections arise from a profound understanding of modern culture and of the difficulties believers encounter in living their faith within a secularized world.

The title The Hidden Stream refers to the Trill Mill Stream, a small branch of the Thames that runs partially concealed beneath the streets of Oxford. Ronald Knox uses this almost invisible watercourse as a metaphor for the action of God and the Church in the world: just as the stream continues to flow beneath the surface and quietly sustains the life of the city, divine grace acts discreetly yet constantly in souls and throughout history. For Knox, not all the intellectual currents of Oxford lead to skepticism; there are also “hidden streams” of faith and truth that continue to nourish spiritual and cultural life.

Ronald Arbuthnott Knox (1888–1957) was one of the most brilliant figures of twentieth-century English Catholicism. The son of an Anglican bishop and the grandson of two other Anglican bishops, he was educated at Eton and Oxford. From an early age, he distinguished himself through his intelligence and his mastery of the classical languages. Ordained first as an Anglican minister, he converted to Catholicism in 1917. He was later ordained a Catholic priest and returned to Oxford as chaplain to Catholic students. One of his greatest achievements was his translation of the Bible into English. Knox remains a key figure in the Catholic intellectual revival of the English-speaking world.