In Catholicism, devotion to the Sacred Heart of Jesus is associated with the idea of Jesus as both human and divine, with the heart representing Jesus' love for humanity. Devotion to the Sacred Heart holds that the heart represents both the human idea of love and the divine concept of love, and is symbolic of Jesus because his actions were driven by both of these ideals.
Devotion to the Sacred Heart emerged in part from the visions of Saint Margaret Mary, a Visitation nun who stated that in visions of Jesus, he had told her that he wanted the symbol of his human heart to be worshipped as a symbol of love and mercy. Saint Margaret Mary became completely devoted to the Sacred Heart for the rest of her life, and kept detailed journals about its importance.
After repeated examinations and discussion, the Catholic Church adopted the devotion to the Sacred Heart, based both on Saint Margaret Mary's visions and the symbolic importance of Christ's human heart, which contained aspects of both humanity and the divine. The Sacred Heart is a powerful symbol of love and mercy within the Catholic Church, and it is often viewed as a source of divine grace.