1) Christian Anthropology: Gaudium et Spes #24 reads: “The Lord Jesus… has opened up new horizons closed to human reason by implying that there is a certain parallel between the union existing among the divine persons and the union of the sons of God in truth and love. It follows, then, that if man is the only creature on earth that God has wanted for its own sake, man can fully discover his true self only in a sincere giving of himself.”
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I preface the next observations, which are from the Word of God, with the Magisterium of Benedict XVI: “the Word of God is the foundation of everything, it is the true reality. And to be realistic, we must rely upon this reality. We must change our notion that matter, solid things, things we can touch, is the most solid, the most certain reality. At the end of the Sermon on the Mount, the Lord speaks to us about the two possible foundations for building the house of one’s life: sand and rock. He who builds on sand only builds on visible and tangible things, on success, on career, on money. Apparently these are the true realities. But all this one day will vanish. We can see this now with the fall of two large banks: this money disappears, it is nothing. And thus all things, which seem to be the true realities we can count on, are only realities of a secondary order. Who builds his life on these realities, on matter, on success, on appearances, builds upon sand. Only the Word of God is the foundation of all reality, it is as stable as the heavens and more than the heavens, it is reality. Therefore, we must change our concept of realism. The realist is he who recognizes the Word of God, in this apparently weak reality, as the foundation of all things. Realist is he who builds his life on this foundation, which is permanent. Thus the first verses of the Psalm invite us to discover what reality is and how to find the foundation of our life, how to build life.”
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2) Since “without me, you can do nothing” (Jn. 15, 5), the prescriptions of the Sermon on the Mount – such as “But I say to you, love your enemies” (Mt. 4, 44) - are certainly impossible. What man, by natural inclination, loves his enemies (who by definition are not loved precisely as enemies)?
3) The act of redemption as the original liberation from the slavery of the flesh-pots of Egypt (and ultimately of the self) is the slaying of the first born of cattle and men, the People of God being saved by the blood of the lamb sprinkled over their doorposts averting the Avenging Angel. The Jews were saved by this sprinkling of blood and renewed this feast of the “Passingover” of death each year by a return to Jerusalem. “Israel had to make a pilgrimage, as it were, to the city every year at Passover in order to return to its origins, to be recreated and to experience once again its rescue, liberation and foundation. A very deep insight lies behind this. In the course of a year, a people is always in danger of disintegrating, not only through external causes, but also interiorly, and of losing hold of the inner motivation which sustains it. It needs to return to its fundamental origin. Passover was intended to be this annual event in which Israel returned from the threatening chaos (which lurks in every people) to its sustaining origin.” 
No Paschal Lamb at the Last Supper:
This was the occasion of the Last Supper (the habhuroth) when Jesus formed the Church at home (not in the Temple) as family (not institution). There was no paschal lamb because Jesus was the Lamb. Benedict XVI clarifies: According to John, Jesus died on the Cross at the very moment when the Passover lambs were being sacrificed in the temple. The death of Jesus and the sacrifice of the lambs coincided.
However, this means that he must have died the day before Easter and could not, therefore, have celebrated the Passover meal in person - this, at any rate, is how it appears.
According to the three Synoptic Gospels, the Last Supper of Jesus was instead a Passover meal into whose traditional form he integrated the innovation of the gift of his Body and Blood.
This contradiction seemed unsolvable until a few years ago. The majority of exegetes were of the opinion that John was reluctant to tell us the true historical date of Jesus’ death, but rather chose a symbolic date to highlight the deeper truth: Jesus is the new, true Lamb who poured out his Blood for us all.
In the meantime, the discovery of the [Dead Sea] Scrolls at Qumran has led us to a possible and convincing solution which, although it is not yet accepted by everyone, is a highly plausible hypothesis. We can now say that John’s account is historically precise.
Jesus truly shed his blood on the eve of Easter at the time of the immolation of the lambs.In all likelihood, however, he celebrated the Passover with his disciples in accordance with the Qumran calendar, hence, at least one day earlier; he celebrated it without a lamb, like the Qumran community which did not recognize Herod’s temple and was waiting for the new temple.
Consequently, Jesus celebrated the Passover without a lamb - no, not without a lamb: instead of the lamb he gave himself, his Body and his Blood. Thus, he anticipated his death in a manner consistent with his words: “No one takes [my life] from me, but I lay it down of my own accord” (Jn 10: 18).
The Action that is Redemption:
John 6, 38: “I have come down from heaven not to do my own will, but the will of him who sent me.”
Joseph Ratzinger comments: “In the Son’s obedience, where both wills become one in a single Yes to the will of the Father, communion takes place between human and divine being. The ‘wondrous exchange,’ the ‘alchemy of being,’ is realized here as a liberating and reconciling communication, which becomes a communion between Creator and creature. It is in the pain of this exchange, and only here, that that fundamental change takes place in man, the change which alone can redeem him and transform the conditions of the world. Here community is born, here the Church comes into being. The act whereby we participate in the Son’s obedience, which involves man’s genuine transformation, is also the only really effective contribution toward renewing and transforming society and the world as a whole. Only where this act takes place is there a change for good – in the direction of the kingdom of God.”
4) The Mass:
Action of Christ as I –Gift: "Ecclesia de Eucharistia:” John Paul II
11. “The Lord Jesus on the night he was betrayed” (1 Cor 11:23) instituted the Eucharistic Sacrifice of his body and his blood. The words of the Apostle Paul bring us back to the dramatic setting in which the Eucharist was born. The Eucharist is indelibly marked by the event of the Lord's passion and death, of which it is not only a reminder but the sacramental re-presentation. It is the sacrifice of the Cross perpetuated down the ages.9 This truth is well expressed by the words with which the assembly in the Latin rite responds to the priest's proclamation of the “Mystery of Faith”: “We announce your death, O Lord”.
The Church has received the Eucharist from Christ her Lord not as one gift – however precious – among so many others, but as the gift par excellence, for it is the gift of himself, of his person in his sacred humanity, as well as the gift of his saving work. Nor does it remain confined to the past, since “all that Christ is – all that he did and suffered for all men – participates in the divine eternity, and so transcends all times”.10
When the Church celebrates the Eucharist, the memorial of her Lord's death and resurrection, this central event of salvation becomes really present and “the work of our redemption is carried out”.11 This sacrifice is so decisive for the salvation of the human race that Jesus Christ offered it and returned to the Father only after he had left us a means of sharing in it as if we had been present there. Each member of the faithful can thus take part in it and inexhaustibly gain its fruits. This is the faith from which generations of Christians down the ages have lived. The Church's Magisterium has constantly reaffirmed this faith with joyful gratitude for its inestimable gift.12 I wish once more to recall this truth and to join you, my dear brothers and sisters, in adoration before this mystery: a great mystery, a mystery of mercy. What more could Jesus have done for us? Truly, in the Eucharist, he shows us a love which goes “to the end” (cf. Jn 13:1), a love which knows no measure.
12. This aspect of the universal charity of the Eucharistic Sacrifice is based on the words of the Saviour himself. In instituting it, he did not merely say: “This is my body”, “this is my blood”, but went on to add: “which is given for you”, “which is poured out for you” (Lk 22:19-20). Jesus did not simply state that what he was giving them to eat and drink was his body and his blood; he also expressed its sacrificial meaning and made sacramentally present his sacrifice which would soon be offered on the Cross for the salvation of all. “The Mass is at the same time, and inseparably, the sacrificial memorial in which the sacrifice of the Cross is perpetuated and the sacred banquet of communion with the Lord's body and blood”.13
The Church constantly draws her life from the redeeming sacrifice; she approaches it not only through faith-filled remembrance, but also through a real contact, since this sacrifice is made present ever anew, sacramentally perpetuated, in every community which offers it at the hands of the consecrated minister. The Eucharist thus applies to men and women today the reconciliation won once for all by Christ for mankind in every age. “The sacrifice of Christ and the sacrifice of the Eucharist are one single sacrifice”.14 Saint John Chrysostom put it well: “We always offer the same Lamb, not one today and another tomorrow, but always the same one. For this reason the sacrifice is always only one... Even now we offer that victim who was once offered and who will never be consumed”.15
The Mass makes present the sacrifice of the Cross; it does not add to that sacrifice nor does it multiply it.16 What is repeated is its memorial celebration, its “commemorative representation” (memorialis demonstratio),17 which makes Christ's one, definitive redemptive sacrifice always present in time. The sacrificial nature of the Eucharistic mystery cannot therefore be understood as something separate, independent of the Cross or only indirectly referring to the sacrifice of Calvary.
13. By virtue of its close relationship t
o the sacrifice of Golgotha, the Eucharist is a sacrifice in the strict sense, and not only in a general way, as if it were simply a matter of Christ's offering himself to the faithful as their spiritual food. The gift of his love and obedience to the point of giving his life (cf. Jn 10:17-18) is in the first place a gift to his Father. Certainly it is a gift given for our sake, and indeed that of all humanity (cf. Mt 26:28; Mk 14:24; Lk 22:20; Jn 10:15), yet it is first and foremost a gift to the Father: “asacrifice that the Father accepted, giving, in return for this total self-giving by his Son, who 'became obedient unto death' (Phil 2:8), his own paternal gift, that is to say the grant of new immortal life in the resurrection”.18
In giving his sacrifice to the Church, Christ has also made his own the spiritual sacrifice of the Church, which is called to offer herself in union with the sacrifice of Christ. This is the teaching of the Second Vatican Council concerning all the faithful: “Taking part in the Eucharistic Sacrifice, which is the source and summit of the whole Christian life, they offer the divine victim to God, and offer themselves along with it”.19
The Mass as Action: Action of Christ as I – Gift: Benedict XVI (“Nuclear Fission”)
Sacramentum Caritatis: “The remembrance of his perfect gift consists not in the mere repetition of the Last Supper, but in the Eucharist itself, that is, in the radical newness of Christian worship. In this way, Jesus left us the task of entering into his ‘hour.’ ‘The Eucharist draws us into Jesus' act of self-oblation. More than just statically receiving the incarnate Logos, we enter into the very dynamic of his self-giving.’ (21) Jesus ‘draws us into himself.’ (22) The substantial conversion of bread and wine into his body and blood introduces within creation the principle of a radical change, a sort of ‘nuclear fission,’ to use an image familiar to us today, which penetrates to the heart of all being, a change meant to set off a process which transforms reality, a process leading ultimately to the transfiguration of the entire world, to the point where God will be all in all” (cf. 1 Cor 15:28).
 Keynote Address, Synod on “The Word of God,” October 7, 2008.
 . Ratzinger, “Behold the Pierced One,” Ignatius (1986) 104.
 Ibid. 92-93.