Blaise Pascal
French mathematician, physicist, inventor and Catholic philosopher (1623–1662), born in Clermont-Ferrand, a child prodigy who by sixteen had already formulated a geometric theorem of his own and who invented the first functioning mechanical calculator in history, the Pascaline, to help his tax-collector father. In physics, his experiments on atmospheric pressure and the vacuum confirmed and extended Torricelli's discoveries, and 'Pascal's principle' concerning the transmission of pressure in fluids bears his name; in mathematics, he laid the foundations of probability theory through his correspondence with Fermat on problems of games of chance, and 'Pascal's triangle' remains today one of the most widely taught mathematical objects in the world. On the night of 23 November 1654 he underwent an intense mystical experience which he called his 'night of fire' and recorded in a brief manuscript, the Memorial, sewn into his clothing and discovered only after his death, in which he speaks of a 'fire' of religious certainty opposed to 'the God of philosophers and scholars'; this experience marked his turn toward Jansenism and the religious community of Port-Royal. The Provincial Letters (1656-57), published under a pseudonym in defence of the Jansenists against the Jesuits, are at once a model of classical French prose and a masterclass in intellectual polemic. His posthumous and unfinished work, the Pensées, a collection of preparatory fragments for a never-completed apology for Christianity, contains some of the most famous formulations in all religious philosophy: 'Pascal's Wager', which argues that, given rational uncertainty about God's existence, it is more rational to bet on belief, since the potential gain (infinite salvation) far outweighs any finite loss; and his description of the human condition as a 'thinking reed', weak and fragile before the universe yet superior to it because, unlike the universe, it knows that it dies.