Blaise Pascal

Pascal's father, a tax official and amateur mathematician, educated his son himself. At twelve the boy discovered the first thirty-two propositions of Euclid on his own; at sixteen he wrote a treatise on conic sections that Descartes refused to believe was a youth's work; at nineteen he built a mechanical calculator to help his father with tax accounts. In 1647 his barometer experiments proved the existence of the vacuum and the weight of air, and in 1654 his correspondence with Fermat on gambling problems founded the theory of probability.

On the night of 23 November of that year he experienced two hours of religious ecstasy and sewed his record of it into his coat lining, carrying it until death: 'Fire. God of Abraham, God of Isaac, God of Jacob, not of the philosophers and scholars.' He threw himself into the Jansenist community of Port-Royal, and in 1656 wrote the Provincial Letters for them, attacking Jesuit moral laxity with satire; the letters are a model of French prose and went on the Index.

He planned a defence of Christianity and left nearly a thousand fragments, edited after his death as the Pensées. Man is a thinking reed, the frailest thing in the universe, but he knows that he dies while the universe knows nothing. Caught between two infinities, he flees from thinking about his condition into diversion. Reason cannot prove God, but it can calculate: if God exists the believer wins everything and the unbeliever loses everything; if not, neither loses much. Ill all his life, he died at thirty-nine.