Sacred Heart, in Roman Catholicism, the mystical-physical heart of Jesus as an object of devotion. In addition to a feast, now celebrated on the Friday of the third week after Pentecost, the devotion includes acts of consecration and honor given to the image of the Sacred Heart. Such images often depict a wounded heart encircled by a crown of thorns and radiating light. Related to this devotion is the feast of the Immaculate Heart of Mary, which is celebrated on the Saturday of the third week after Pentecost. The iconography for the Immaculate Heart is similar to that of the Sacred Heart but features a crown of roses rather than thorns and often a heart pierced with a sword.
Whereas the Sacred Heart of Jesus symbolizes Jesus’ love for humanity, the Immaculate Heart of Mary symbolizes Mary’s love for God.
The use of Jesus’ heart to symbolize his love for humanity is found not in the Bible but in the writings of medieval mystics. The devotion was fostered by Carthusian and Jesuit priests and promoted by St. Francis de Sales and St. John Eudes in particular. In 1648 Eudes wrote the first mass and divine office (a public service of praise and worship performed at specific times of the day and night) in honor of the Immaculate Heart of Mary and in 1672 the first mass and divine office for the Sacred Heart of Jesus.
The devotion to the Sacred Heart became especially popular following the disclosure of private revelations to a French Visitandine nun, St. Margaret Mary Alacoque, in the late 17th century. Assisted by Claude de la Colombière, her confessor, she called for the establishment of a feast in honor of the Sacred Heart and for prayers of reparation for sins, especially for those directed against the Eucharist. In 1856 Pope Pius IX introduced the feast into the general calendar of the Roman Catholic Church.