Margaret Mary Alacoque was a 17th-century French nun and mystic from Burgundy. Born in 1647, she entered the Visitation Convent in Paray-le-Monial after experiencing visions of Jesus Christ. She is primarily recognized for her role in spreading devotion to the Sacred Heart of Jesus, a practice that transformed modern Catholic piety. Her spiritual experiences included visions that emphasized the profound love of Christ and the need for humanity to offer reparation for indifference toward his sacrifice.