Blaise Pascal (June 19, 1623-August 19, 1662) was a French philosopher, mathematician, and physicist known for his work with fluids and in probability theory. His work with fluids produced Pascal's law, which states that contained fluids transmit pressure equally in all directions. A member of the Jansenist religious movement, he wrote his Provincial Letters (1656-57) in response to the Jesuits' charge of heresy against Jansenism. These letters helped to form a modern style of French prose. He published Pensées (1669), a collection of his thoughts on Theology and Philosophy.