Preparations were being made to treat it surgically when on 24 March 1656 the child declared herself cured from placing her eye against a reliquary containing part of Christ's crown of thorns.

Father François Annat, Jesuit and confessor of the king, responded with Le Rabat-joie des jansénistes.

[5] Without questioning the reality of the miracle, which was recognized by the church, he strongly attacked Port-Royal and interpreted the event as an invitation from God to abandon the Jansenist heresy.

[6] According to Gilberte Périer in her Vie de Pascal, her brother experienced renewed certainty and joy by the grace of God to his goddaughter.

In 1700, on the request of her brother Canon Louis Périer, she accepted the charge of running the Hôtel-Dieu in Clermont-Ferrand, but gave up this position in 1702 in a difficult political environment.

[1] She devoted herself to charitable works, settled permanently with her brother in Clermont-Ferrand and founded a mission in Cournon-d'Auvergne.

An ex-voto painting of the young Marguerite Périer kneeling at the altar that held the reliquary was completed in 1657 and has been preserved.