You can read more about Jansenism on http://en.wikipedia.org/wiki/Jansenism.Following the death of one of their leaders, Father Francois de Paris, members of a heretical group of Catholics called Jansenists started gathering at his grave and through prayer began performing thousands of miraculous acts of healing, ranging from cancerous tumors to blindness.
Both the Catholic Church and Louis XV saw the Jansenists as a threat to their power [...] the Church had no choice but to declare them the work of the devil, and when Louis XV tried to close the cemetery where Father de Paris was buried, Voltaire dryly commented, "God is fobidden by order of the King to perform any more miracles in the cemetery of Saint-Medard."
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There were so many witnesses, and so much written about these phenomena, which lasted for decades, that the Scottish philosopher, David Hume wrote in his Philosophical Essays:
"There surely never was so great a number of miracles ascribed to one person as those which were lately said to have been wrought in France upon the tomb of Abbe Paris. Many of the miracles were immediately proven on the spot, before judges of unquestioned credit and distinction, in a learned age, and on the most eminent theatre that is now in the world."
Even a member of the French Parliament, Basil Carre de Montgeron, witnessed so many of these miracles that they eventually took up four thick volumes, which he published in 1737 under the name, La Verite des Miracles, and today, even though the Church vigorously opposed these miracles as a threat to their own secular power, The Catholic Encyclopedia today has this to say about the Jansenist miracles[...]
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