Jansenism was an empassioned and rigid Christian movement which was popular in the second half of the 17th century. It was named after Cornelis Jansen (1585-1638), a Flemish bishop, who wrote the Augustinus, which was published (posthumously) in 1640. It required of its followers absolute piety and strictly moral ethics.

Jansen's Augustinus states that only through divine intervention can man be good, and only by the grace of God can one be protected from earthly pleasures. The clause is that this intervention is not granted to all; it is predestiny which determines one state of salvation.

Jansen further states that Christ did not come into the world to save everyone, just a small chosen number, and that God was capable of refusing grace, even to good people.

The creation of the Augustinus was undertaken by Jansen, and his good buddy, Jean Duvergier, the abbot of Saint-Cyran, in 1621 as an attempt to bring the doctrine of Saint Augustine closer to the rigid Calvinist theology, though Jansen claimed to be in no way Protestant, and added that the only route to salvation was through the Roman Catholic church.

After Jansen succumbed to the effects of the plague, and the subsequent publication of the Augustinus, the Jesuits revolted and threw the abbot in jail. His follower, Antoine Arnault, took over to become the fervent defender of Jansenism in France.

The new doctrinal centre of Jansenism was set up near Paris in the abbey of Port-Royal-des-Champs. The abbey was a place where intellectuals, nobles, royal judges often took religious retreats.

In the 1650s, the Counter Reformation was at its peak, and Jansenists and Jesuits began to conflict, with every member of society taking a side. The Jesuits saw the predestination of grace as a defense for a libertine lifestyle.

In 1709, the abbey at Port-Royal-des-Champs was razed by order of King Louis XIV, and an edict, Unigenitus, was sent out by the pope to destroy the works of the Jansenists.

During the 1700s, hundreds of clergymen ignored the bull Unigenitus, and the movement spread to Spain, then Italy and Austria. In the 1750s, a number of bishops tried to deny the Jansenists their last rites, and there was a major clash between the courts and the government. In the 1760s, the Jesuits were expulsed from France, so it is needless to say that there was much celebration in Jansenist camps. However, the movement eventually dwindled away to essentially zero involement.