"The Provincial Letters" is a series of 18 letters written by a philosopher and mathematician, where he defends his friend Antoine Arnauld, an opponent of the Jesuits, who was on trial before the faculty of theology in Paris for his controversial religious works. The letters mockingly criticize the morals and ethics of Jesuits, and the casuistry they used to justify moral laxity, while also debating various philosophical and theological issues. The letters are considered a masterpiece of French prose and had a significant influence on the French language.

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