Pascal, Blaise 1623-62
French mathematician, physicist, theologian and man-of-letters

He was born in Clermont-Ferrand, the son of the local president of the court of exchequer. When his mother died, the family moved to Paris (1630), where his father, a considerable mathematician, educated his children. Pascal was not allowed to begin a subject until his father thought he could easily master it, and by the age of 11 had worked out for himself in secret the first 23 propositions of Euclid, calling straight lines 'bars' and circles 'rounds'. Inspired by the work of Girard Desargues, at 16 he published an essay on conics which Ren� Descartes refused to believe was the work of a youth. It contains his famous theorem on a hexagram inscribed in a conic. Father and son collaborated in experiments to confirm Evangelista Torricelli's theory, unpalatable to the schoolmen, that nature does not, after all, abhor a vacuum. They carried up the Puy de D�me two glass tubes containing mercury, inverted in a bath of mercury, and noted the fall of the mercury columns with increased altitude. This led on to the invention of the barometer, the hydraulic press and syringe. In 1647, he patented a calculating machine, later simplified by Gottfried Leibniz, built to assist his father in his accounts. In 1651 Pascal's father died, his sister, Jacqueline, entered the Jansenist convent at Port-Royal, and Pascal divided his time between mathematics and socializing. His correspondence with Pierre de Fermat in 1654 laid the foundations of probability theory. That year he had the first of two religious revelations, according to a note found sewn into his clothes. He joined his sister in her retreat at Port-Royal, gave up mathematics and society almost completely and joined battle for the Jansenists against the Jesuits of the Sorbonne who had publicly denounced Antoine Arnauld, the Jansenist theologian and mathematician, as a heretic. In 18 anonymous pamphlets, the Lettres provinciales (1656-57), Pascal attacked the Jesuits' meaningless jargon, casuistry and moral laxity. This early prose masterpiece in the French language, the model for Voltaire, failed to save Arnauld, but undermined for ever Jesuit authority and prestige. In 1669 Pascal's papers on the area of the cycloid heralded the invention of the integral calculus. Notes for a casebook of Christian truths were discovered after his death, and published as the Pens�es in 1669. They contain profound insights into religious truths coupled with scepticism of rationalist thought and theology. Their style owes much to Michel de Montaigne and Pierre Charron.

Bibliography: Morris Bishop, Pascal, the Life of a Genius (1936)