The popular Catholic revival of the nineteenth century was preceded by an intellectual revolution that enabled the Catholic Church to overcome its traditional suspicion of popular religious practices. Central to this transformation was the elaboration of the moral-theological doctrine of equiprobabilism in response to rigorist Augustinian moral pessimism, most fruitfully by Alphonsus of Liguori (1696-1787). His moral theology would set the Church in confrontation with the Catholic Enlightenment. On account of this shift in moral theology, Catholicism was best able of the major Christian churches to preserve within its institutional fold the broad religious revival of the nineteenth century.