Is "the heart" still a relevant symbol of God's love in today's world? In his fourth encyclical, Pope Francis affirms the centrality and significance of the Sacred Heart in the history, theology, devotion, and missionary life of the Church. After reflecting on the Christian meaning of "the heart," he explores the scriptural, magisterial, and spiritual grounds for devotion to the Heart of Jesus and invites the Church to conversion, reparation, and social action informed by the burning love of Christ.