These constitute a scathing attack on the moral and theological views of the Jesuits, who were the most vociferous opponents of both Arnauld and Jansenism. In this debate the Jesuits were somewhat unfairly represented as a religious faction which engaged in deliberate deception for political ends and sacrificed doctrine to morals, and Jansenists were for their part depicted as crypto-Calvinists whose interpretation of St Augustine was both erroneous and heretical. Pascal and his co-authors tried vigorously to rebut the charge of heresy levelled at Jansen’s writings while still acknowledging the authority of the Church that as Roman Catholics they were bound to accept. As it transpired, the debate was won de facto by the Jesuits; the Lettres provinciales were placed on the Index of Forbidden Books in 1657, and the Jansenist movement itself was condemned by the Pope shortly after. But the wit of the letters and their dazzling display of satire and irony have ensured that the judgment of posterity has been accorded to Pascal’s side, at least in literary terms.

For all that, the school at Port-Royal was closed in 1661, and the remaining solitaires and nuns were forced to sign a document to mark their submission to the Roman Catholic Church; this prompted Pascal to write the Écrit sur la signature du formulaire (Tract on the signing of the formulary), urging Port-Royalists not to sign. In it he reiterated the defence of Jansenism which is found in the Lettres provinciales, distinguishing between fact and faith or law in matters of religion. Councils, Fathers of the Church and popes are infallible on matters of faith, but not on matters of fact, and Pascal contends that the identification of Jansenism with heresy is a matter of fact, not law. The Écrit was never published because Nicole and Arnauld contradicted Pascal’s advice. After a stormy altercation with them, Pascal renounced all further engagement in religious controversy. Instead he devoted his final months of life to the poor of the part of Paris in which he lived, not only making over all his worldly goods to them, but also organizing what was in effect the world’s first omnibus service, which carried passengers from one part of Paris to another for a fixed fare.