The Son of God, who came down “from heaven, not to do (his) own will, but the will of him who sent (him)”,said on coming into the world, “Lo, I have come to do your will, O God.” “and by that will we have been sanctified through the offering of the body of Jesus Christ once for all.” From the first moment of his Incarnation the Son embraces the Father’s plan of divine salvation in his redemptive mission: “My food is to do the will of him who sent me, and to accomplish his work.” The sacrifice of Jesus “for the sins of the whole world” expresses his loving communion with the Father. “The Father loves me, because I lay down my life”, said the Lord, “(for) I do as the Father has commanded me, so that the world may know that I love the Father.”
The desire to embrace his Father’s plan of redeeming love inspired Jesus’ whole life,for his redemptive passion was the very reason for his Incarnation. and so he asked, “and what shall I say? ‘Father, save me from this hour’? No, for this purpose I have come to this hour.” and again, “Shall I not drink the cup which the Father has given me?”From the cross, just before “It is finished”, he said, “I thirst.”
After agreeing to baptize him along with the sinners, John the Baptist looked at Jesus and pointed him out as the “Lamb of God, who takes away the sin of the world”. By doing so, he reveals that Jesus is at the same time the suffering Servant who silently allows himself to be led to the slaughter and who bears the sin of the multitudes, and also the Paschal Lamb, the symbol of Israel’s redemption at the first Passover.Christ’s whole life expresses his mission: “to serve, and to give his life as a ransom for many.”
By embracing in his human heart the Father’s love for men, Jesus “loved them to the end”, for “greater love has no man than this, that a man lay down his life for his friends.” In suffering and death his humanity became the free and perfect instrument of his divine love which desires the salvation of men. Indeed, out of love for his Father and for men, whom the Father wants to save, Jesus freely accepted his Passion and death: “No one takes [my life] from me, but I lay it down of my own accord.” Hence the sovereign freedom of God’s Son as he went out to his death.
Jesus gave the supreme expression of his free offering of himself at the meal shared with the twelve Apostles “on the night he was betrayed”. On the eve of his Passion, while still free, Jesus transformed this Last Supper with the apostles into the memorial of his voluntary offering to the Father for the salvation of men: “This is my body which is given for you.” “This is my blood of the covenant, which is poured out for many for the forgiveness of sins.”
The Eucharist that Christ institutes at that moment will be the memorial of his sacrifice. Jesus includes the apostles in his own offering and bids them perpetuate it. By doing so, the Lord institutes his apostles as priests of the New Covenant: “For their sakes I sanctify myself, so that they also may be sanctified in truth.”
From the Catechism of the Catholic Church 606-611