11..."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”.
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”. 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. 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”....

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...34.The Eucharist thus appears as the culmination of all the sacraments in perfecting our communion with God the Father by identification with his only-begotten Son through the working of the Holy Spirit. With discerning faith a distinguished writer of the Byzantine tradition voiced this truth:"in the Eucharist “unlike any other sacrament, the mystery [of communion] is so perfect that it brings us to the heights of every good thing: here is the ultimate goal of every human desire, because here we attain God and God joins himself to us in the most perfect union”Precisely for this reason it is good to cultivate in our hearts a constant desire for the sacrament of the Eucharist. This was the origin of the practice of “spiritual communion”, which has happily been established in the Church for centuries and recommended by saints who were masters of the spiritual life.  (1)