From the Encyclical Haurietis Aquas, on Devotion to the Sacred Heart, By Pope Pius XII

35. The mystery of the divine redemption is primarily and by its very nature a mystery of love, that is, of the perfect love of Christ for His heavenly Father to Whom the sacrifice of the Cross, offered in a spirit of love and obedience, presents the most abundant and infinite satisfaction due for the sins of the human race; “By suffering out of love and obedience, Christ gave more to God than was required to compensate for the offense of the whole human race.“(30)

36. It is also a mystery of the love of the Most Holy Trinity and of the divine Redeemer towards all men. Because they were entirely unable to make adequate satisfaction for their sins,(31) Christ, through the infinite treasure of His merits acquired for us by the shedding of His precious Blood, was able to restore completely that pact of friendship between God and man which had been broken, first by the grievous fall of Adam in the earthly paradise and then by the countless sins of the chosen people.

37. Since our divine Redeemer as our lawful and perfect Mediator, out of His ardent love for us, restored complete harmony between the duties and obligations of the human race and the rights of God, He is therefore responsible for the existence of that wonderful reconciliation of divine justice and divine mercy which constitutes the sublime mystery of our salvation. On this point the Angelic Doctor wisely comments: “That man should be delivered by Christ’s Passion was in keeping with both His mercy and His justice. With His justice, because by His Passion Christ made satisfaction for the sins of the human race, and so man was set free by Christ’s justice; and with His mercy, for since man of himself could not satisfy for the sin of all human nature, God gave him His Son to satisfy for him. And this came of a more copious mercy than if he had forgiven sins without satisfaction: Hence St. Paul says: ‘God, who is rich in mercy, by reason of His very great love wherewith He has loved us even when we were dead by reason of our sins, brought us to life together with Christ.‘”(32)