The devotion to the Sacred Heart (also known as the Most Sacred Heart of Jesus, Sacratissimum Cor Iesu in Latin) is one of the most widely practiced and well-known Roman Catholic devotions, taking Jesus Christ′s physical heart as the representation of his divine love for humanity.
This devotion is predominantly used in the Roman Catholic Church and in a modified way among some high-church Anglicans, Lutherans and Eastern Catholics. The devotion is especially concerned with what the Church deems to be the longsuffering love and compassion of the heart of Christ towards humanity. The popularization of this devotion in its modern form is derived from a Roman Catholic nun from France, Saint Margaret Mary Alacoque, who said she learned the devotion from Jesus during a series of apparitions to her between 1673 and 1675, and later, in the 19th century, from the mystical revelations of another Roman Catholic nun in Portugal, Blessed Mary of the Divine Heart, a religious of the Good Shepherd, who requested in the name of Christ that Pope Leo XIII consecrate the entire world to the Sacred Heart of Jesus. Predecessors to the modern devotion arose unmistakably in the Middle Ages in various facets of Catholic mysticism, particularly with Saint Gertrude the Great.