A nun of the Visitation order, Margaret Mary was most notably known for her visions of Our Lord and devotion to His Sacred Heart.
"And He [Christ] showed me that it was His great desire of being loved by men and of withdrawing them from the path of ruin that made Him form the design of manifesting His Heart to men, with all the treasures of love, of mercy, of grace, of sanctification and salvation which it contains, in order that those who desire to render Him and procure Him all the honor and love possible, might themselves be abundantly enriched with those divine treasures of which His heart is the source." — from Revelations of Our Lord to St. Mary Margaret Alacoque