75 Let us now turn to the Holy Spirit, whose fire fills the heart of Christ. As Saint John Paul II once said, Christ’s heart is “the Holy Spirit’s masterpiece”. This is more than simply a past event, for even now “the heart of Christ is alive with the action of the Holy Spirit, to whom Jesus attributed the inspiration of his mission (cf. Lk 4:18; Is 61:1) and whose sending he had promised at the Last Supper. It is the Spirit who enables us to grasp the richness of the sign of Christ’s pierced side, from which the Church has sprung (cf. Sacrosanctum Concilium , 5)”. In a word, “only the Holy Spirit can open up before us the fullness of the ‘inner man’, which is found in the heart of Christ. He alone can cause our human hearts to draw strength from that fullness, step by step”.
Source: Dilexit Nos (Vatican.va)