Her younger brother, Antoine Arnauld, 1612-94, was a leading Jansenist controversialist. He was a priest and a member of the Sorbonne. His best-known work was an attack on the Jesuits, De la fréquente communion (1643). He also wrote against Calvinism and the freethinkers. In 1656 he was expelled from the Sorbonne and the faculty of theology. He lived for some years at Port-Royal-des-Champs, where he collaborated on the Port-Royal textbooks. He withdrew to Belgium in 1679. The chief controversy of his later years was with Malebranche on the theology of grace.
His elder brother, Robert Arnauld d'Andilly, 1588-1674, was a translator of religious writings and a religious poet of originality. He lived for many years in retirement at Port-Royal-des-Champs.
See biography of Marie Angélique de Sainte Madeleine by M. L. Trouncer (1957).