Blaise Pascal, The precociously brilliant contemporary of Descartes, was a gifted mathematician and physicist. The Pensées (""Thoughts"") is a collection of fragments. Pascal's religious conversion led him into a life of asceticism, and The Pensées was in many ways his life's work. It represented Pascal's defense of the Christian religion, and the concept of ""Pascal's wager"" stems from a portion of this work. The Pensées is the name given posthumously to fragments that Pascal had been preparing for an apology for Christianity, which was never completed. That envisioned work is often referred to as the Apology for the Christian Religion, although Pascal never used that title.