She became the great protectress of the Jansenists; it was in her house that Arnauld, Nicole and De Lane were protected; and to her influence must be in great part attributed the release of Lemaistre De Sacy from the Bastille, the introduction of Pomponne into the ministry and of Arnauld to the king.
Among the mendicant friars of the 13th century, among the Jansenists, the early Quakers, the converts of Wesley and Whitefield, the persecuted protestants of the Cevennes, the Irvingites.
In 1730 he entered the Mazarin College under the Jansenists, who soon perceived his exceptional talent, and, prompted perhaps by a commentary on the Epistle to the Romans which he produced in the first year of his philosophical course, sought to direct it to theology.
He favoured the Jesuits, especially in their conflict with the Jansenists, forbade in 1661 the translation of the Roman Missal into French, and in 1665 canonized Francis of Sales.
In the struggle against the Jansenists he used all the influence he had with the clergy to secure the passage of the apostolic constitution of the 31st of March 16 J3 (Relation de ce qui s'est fait depuis 1653 Bans les assemblies des iveques au sujet des cinq propositions, 1657); but in the rebellion raised by Retz, archbishop of Paris, against the king, he took the part of the king against the pope.