Antoine Arnauld, a Jansenist theologian and Cartesian philosopher, was one of the most skilled philosophical and theological controversialists of the seventeenth century. His reputation was such that he was known in the early modern period as le grand Arnauld. Arnauld was born in Paris on February 8, 1612, the last of twenty children of Catherine Marion de Druy and the elder Antoine Arnauld. Arnauld's father served as an attorney for Queen Catherine de Médicis, and at the beginning of the seventeenth century he successfully argued the case in the Parlement de Paris for the expulsion of the Jesuits from France. Arnauld's sister, Mère Angélique Arnauld, was installed as abbess of Port-Royal des Champs at the age of thirteen and became a prominent member of the convent. Though Arnauld initially intended to follow in his father's footsteps by becoming a lawyer, he later changed...