149 At times, we may be tempted to consider this mystery of love as an admirable relic from the past, a fine spirituality suited to other times. Yet we need to remind ourselves constantly that, as a saintly missionary once said, “this divine heart, which let itself be pierced by an enemy’s lance in order to pour forth through that sacred wound the sacraments by which the Church was formed, has never ceased to love”. More recent saints, like Saint Pius of Pietrelcina, Saint Teresa of Calcutta and many others, have spoken with deep devotion of the heart of Christ. Here I would also mention the experiences of Saint Faustina Kowalska, which re-propose devotion to the heart of Christ by greatly emphasizing the glorious life of the risen Lord and his divine mercy. Inspired by her experiences and the spiritual legacy of Saint Józef Sebastian Pelczar (1842-1924), Saint John Paul II intimately linked his reflections on divine mercy with devotion to the heart of Christ: “The Church seems in a singular way to profess the mercy of God and to venerate it when she directs herself to the heart of Christ. In fact, it is precisely this drawing close to Christ in the mystery of his heart which enables us to dwell on this point of the revelation of the merciful love of the Father, a revelation that constituted the central content of the messianic mission of the Son of Man”. Saint John Paul also spoke of the Sacred Heart in very personal terms, acknowledging that, “it has spoken to me ever since my youth”.
Source: Dilexit Nos (Vatican.va)