Ven. Pius XII : " Wherefore, that the redemption and salvation of each person and of future generations unto the end of time may be effectively accomplished, and be acceptable to God, it is necessary that-men should individually come into vital contact with the sacrifice of the cross, so that the merits, which flow from it, should be imparted to them. In a certain sense it can be said that on Calvary Christ built a font of purification and salvation which He filled with the blood He shed; but if men do not bathe in it and there wash away the stains of their iniquities, they can never be purified and saved."
ON THE SACRED LITURGY
75. It is easy, therefore, to understand why the holy Council of Trent lays down that by means of the eucharistic sacrifice the saving virtue of the cross is imparted to us for the remission of the sins we daily commit.
76. Now the Apostle of the Gentiles proclaims the copious plenitude and the perfection of the sacrifice of the cross, when he says that Christ by one oblation has perfected for ever them that are sanctified. For the merits of this sacrifice, since they are altogether boundless and immeasurable, know no limits; for they are meant for all men of every time and place. This follows from the fact that in this sacrifice the God-Man is the priest and victim; that His immolation was entirely perfect, as was His obedience to the will of His eternal Father; and also that He suffered death as the Head of the human race: "See how we were bought: Christ hangs upon the cross, see at what a price He makes His purchase . . . He sheds His blood, He buys with His blood, He buys with the blood of the Spotless Lamb, He buys with the blood of God's only Son. He who buys is Christ; the price is His blood; the possession bought is the world."
77. This purchase, however, does not immediately have its full effect; since Christ, after redeeming the world at the lavish cost of His own blood, still must come into complete possession of the souls of men. Wherefore, that the redemption and salvation of each person and of future generations unto the end of time may be effectively accomplished, and be acceptable to God, it is necessary that-men should individually come into vital contact with the sacrifice of the cross, so that the merits, which flow from it, should be imparted to them. In a certain sense it can be said that on Calvary Christ built a font of purification and salvation which He filled with the blood He shed; but if men do not bathe in it and there wash away the stains of their iniquities, they can never be purified and saved.
78. The cooperation of the faithful is required so that sinners may be individually purified in the blood of the Lamb. For though, speaking generally, Christ reconciled by His painful death the whole human race with the Father, He wished that all should approach and be drawn to His cross, especially by means of the sacraments and the eucharistic sacrifice, to obtain the salutary fruits produced by Him upon it. Through this active and individual participation, the members of the Mystical Body not only become daily more like to their divine Head, but the life flowing from the Head is imparted to the members, so that we can each repeat the words of St. Paul, "With Christ I am nailed to the cross: I live, now not I, but Christ liveth in me." We have already explained sufficiently and of set purpose on another occasion, that Jesus Christ "when dying on the cross, bestowed upon His Church, as a completely gratuitous gift, the immense treasure of the redemption. But when it is a question of distributing this treasure, He not only commits the work of sanctification to His Immaculate Spouse, but also wishes that, to a certain extent, sanctity should derive from her activity."
79. The august sacrifice of the altar is, as it were, the supreme instrument whereby the merits won by the divine Redeemer upon the cross are distributed to the faithful: "as often as this commemorative sacrifice is offered, there is wrought the work of our Redemption." This, however, so far from lessening the dignity of the actual sacrifice on Calvary, rather proclaims and renders more manifest its greatness and its necessity, as the Council of Trent declares. Its daily immolation reminds us that there is no salvation except in the cross of our Lord Jesus Christ and that God Himself wishes that there should be a continuation of this sacrifice "from the rising of the sun till the going down thereof," so that there may be no cessation of the hymn of praise and thanksgiving which man owes to God, seeing that he required His help continually and has need of the blood of the Redeemer to remit sin which challenges God's justice.