The central controversy surrounding Jansenism concerned its alleged heterodoxy in respect to divine grace and human liberty. Five propositions regarding fallen human nature, the operation of grace, and the ability of man to cooperate with it were extracted from Jansen’s Augustinus, and condemned by Innocent X in 1653. The Jansenists denied that they maintained the propositions in the condemned sense. Their position was framed against a teaching developed by Molina and other Jesuits (analysed in section II), which, they claimed, attributed so much power to fallen nature as to fall into Pelagianism. The chapter balances accounts which relate the Jansenists’ moral rigorism wholly to their pessimistic assessment of human nature and their predestinarianism. They aimed to establish human freedom and the responsibility of each individual for his own conversion, and the counterpoint to their view of the fall was a mystical optimism regarding the destiny of nature under grace.