78 In numerous ways, Christ’s heart has always been present in the history of Christian spirituality. In the Scriptures and in the early centuries of the Church’s life, it appeared under the image of the Lord’s wounded side, as a fountain of grace and a summons to a deep and loving encounter. In this same guise, it has reappeared in the writings of numerous saints, past and present. In recent centuries, this spirituality has gradually taken on the specific form of devotion to the Sacred Heart of Jesus.
Source: Dilexit Nos (Vatican.va)