Intellectually, Blaise Pascal grew rapidly to the stature and strength of a giant; his genius showing itself mainly in the direction of mathematics; at the age of fifteen his studies on conic sections were thought worthy to be read before the most scientific men of Paris, and in after years of agonizing pain mathematical research alone was able to calm him, and distract his mind from himself. His actual reading was at all times narrow, and his scholarship was not profound. In 1646, his father, having broken his thigh at Rouen, came under the influence of two members of the Jansenist school of thought at that place, who attended him in his illness, and from that time dated the more serious religious views of the family. Jaqueline was from the first deeply affected by the more rigorous opinions with which she came in contact. Forbidden to enter the cloister, she lived at home as austere a life as though she had been professed, but after her father's death won her brother's reluctant consent to take the veil at Port Royal, and became one of the strictest nuns of that rigid rule.
Blaise Pascal went through a double process of conversion. When the family first fell under Jansenist influence he threw himself so earnestly into the study of theology that he seriously injured his frail health, and being advised to refrain from all intellectual labour, he returned to the world of Paris, where his friends the Duc de Roannez, the Chevalier de Méré and M. Miton were among the best known and most fashionable persons. His father's death put him in possession of a fair fortune, which he used freely, not at all viciously, but with no renunciation of the pleasures of society. There is some evidence of a proposal that he should marry the Duc de Roannez' sister, and no doubt with such a scheme before him he wrote his celebrated "Discours sur les Passions de l'Amour." This, however, resulted only in the conversion of the duke and his sister, the latter of whom for a time, the former for the whole of his life, remained subject to the religious feelings then excited...