The Sacred Heart is a symbol of Jesus Christ's love and compassion for humanity, particularly in the Catholic Church. The story of the Sacred Heart goes back to the Middle Ages when mystics and saints, such as St. Gertrude the Great, had visions of Christ's heart burning with love for humanity.

The devotion to the Sacred Heart became more popular in the 17th century when St. Margaret Mary Alacoque, a French nun, had a series of visions of Jesus Christ's Sacred Heart. In these visions, Jesus revealed to St. Margaret Mary his deep love for humanity and his desire for a special devotion to be established in honor of his Sacred Heart.

Through St. Margaret Mary's efforts and the support of her Jesuit confessor, St. Claude de la Colombiere, the devotion to the Sacred Heart became widespread. In 1765, Pope Clement XIII officially approved the devotion, and in 1856, Pope Pius IX extended the Feast of the Sacred Heart to the entire Catholic Church.

Today, the Sacred Heart remains an important symbol of Christ's love and mercy, and is often depicted in Catholic art and iconography as a heart surrounded by thorns, with flames emanating from it, and sometimes crowned with a cross. The devotion to the Sacred Heart is often practiced through acts of reparation, such as making a Holy Hour, receiving Holy Communion on the First Friday of the month, and offering prayers and sacrifices in honor of the Sacred Heart.