The mathematician, philosopher and scientist Blaise Pascal was born in Clermont-Ferrand, France. His father educated him at home, and refused to let him study mathematics before he was 15 years old. Not surprisingly, perhaps, this had the effect of making Pascal intensely curious about mathematics, and he proved several geometric theorems to himself by age 12 without any external help.
Pascal was a mathematical prodigy, but he also had broader scientific interests. He invented a mechanical calculator in 1642, to help his father in his tax work as a government official, and carried out important research on hydrostatics and atmospheric pressure. He argued that the space at the top of a mercury barometer contained a vacuum, which contradicted the received view that a vacuum is impossible in principle. He demonstrated that the column of mercury is supported by atmospheric pressure by performing experiments showing that the height of the mercury column decreases at higher altitudes.
His health was always poor, and in the early 1650s he was advised to avoid his usual intense intellectual activity. He went to Paris to attempt to distract himself from his work, and took up the popular gambling games that led to his interest in probability. However, this lifestyle didn't agree with him, and he suffered from severe depression.
In 1654 Pascal had a religious experience which led him to spend much time at the Jansenist monastery at Port-Royal, although he didn't become a monk. In the last years of his life, he wrote more on theological matters than on mathematics. He died of cancer at age 39, leaving an unfinished manuscript of his most important philosophical work, the Pensées (Thoughts). This work contains his famous wager: "God is or He is not...Let us weigh the gain and the loss in choosing...'God is'. If you gain, you gain all, if you lose, you lose nothing. Wager, then, unhesitatingly, that He is."