The document discusses the origins and development of the devotion to the Sacred Heart of Jesus. It began in the 11th-12th centuries in Benedictine and Cistercian monasteries. In 1670, the first Feast of the Sacred Heart was celebrated in Rennes, France. Jesus then appeared to Saint Margaret Mary Alacoque and asked her to promote the devotion to His Sacred Heart. Though faced skepticism, she promoted the devotion with her spiritual director. This helped popularize the devotion to Jesus' physical heart as a symbol of His redemptive love. The devotion was then adopted by several Catholic saints and religious orders.