Blaise Pascal was a child prodigy whose genius touched mathematics, physics, and philosophy. At age 19, he invented the 'Pascaline,' one of the first mechanical calculators. In physics, his work on fluids and atmospheric pressure led to the unit of pressure, the 'Pascal,' being named after him. He is most famous in mathematics for 'Pascal's Triangle' and for co-founding probability theory through his correspondence with Fermat regarding a gambling dispute. In his later life, he turned to religious philosophy, writing 'Pensées,' where he proposed 'Pascal's Wager'—the logical argument that it is safer to believe in God than not to, given the infinite stakes involved.