How much of our own self-interest should we be willing to sacrifice for love of another? The Quietists answered, all of it, even the salvation of our own soul. Opposing them were the Jansenists, including Arnauld, who saw self-interest as inescapable. The debate swept across French society in the 17th century, with Bossuet and Fenelon on opposite sides, and was multi-dimensional, with political and ecclesiastical intrigue, charges of heresy, and many shenanigans. Initially theological, the debate's basis lay in differing philosophical concepts of freewill, with both sides claiming support from Descartes's views. The debate thus highlights interpretation of the Cartesians, especially Malebranche, a prominent participant in it. Nevertheless, this is the first book on the debate in English.