The Holy Father’s sermon for the Mass of the Last Supper on Holy Thursday.
Pope Benedict teases out three sayings from the Lord’s discourse at the Last Supper in the Gospel of John.
1) "This is eternal life, that they may know you, the only true God, and Jesus Christ, whom you have sent" (Jn 17:3)
2) "I have made your name known to those whom you gave me from the world" (v. 6). "I have made your name known to them, and I will make it known, so that the love with which you have loved me may be in them, and I in them" (v. 26)
3) "I do not ask only on behalf of these – the community of the disciples gathered in the Upper Room – but also on behalf of those who will believe in me through their word, that they may all be one. As you, Father, are in me, and I am in you, may they also be in us, so that the world may believe that you have sent me" (v. 20ff.; cf. vv. 11 and 13)
My emphases and comments.
Dear Brothers and Sisters,
In his Gospel, Saint John, more fully than the other three evangelists, reports in his own distinctive way the farewell discourses of Jesus; they appear as his testament and a synthesis of the core of his message. They are introduced by the washing of feet, in which Jesus’ redemptive ministry on behalf of a humanity needing purification is summed up in a gesture of humility. Jesus’ words end as a prayer, his priestly prayer, whose background exegetes have traced to the ritual of the Jewish feast of atonement. The significance of that feast and its rituals – the world’s purification and reconciliation with God – is fulfilled in Jesus’ prayer, a prayer which anticipates his Passion and transforms it into a prayer. The priestly prayer thus makes uniquely evident the perpetual mystery of Holy Thursday: the new priesthood of Jesus Christ and its prolongation in the consecration of the Apostles, in the incorporation of the disciples into the Lord’s priesthood. From this inexhaustibly profound text, I would like to select three sayings of Jesus which can lead us more fully into the mystery of Holy Thursday.
First, there are the words:  "This is eternal life, that they may know you, the only true God, and Jesus Christ, whom you have sent" (Jn 17:3). Everyone wants to have life. We long for a life which is authentic, complete, worthwhile, full of joy. This yearning for life coexists with a resistance to death, which nonetheless remains unescapable. [Which is at the heart of why we must worship God and not distract ourselves by introducing that which is unworthy in our worship.] When Jesus speaks about eternal life, he is referring to real and true life, a life worthy of being lived. He is not simply speaking about life after death. He is talking about authentic life, a life fully alive and thus not subject to death, yet one which can already, and indeed must, begin in this world. [Though it can only be fulfilled in the next.] Only if we learn even now how to live authentically, if we learn how to live the life which death cannot take away, does the promise of eternity become meaningful. But how does this happen? What is this true and eternal life which death cannot touch? We have heard Jesus’ answer: this is eternal life, that they may know you – God – and the one whom you have sent, Jesus Christ. Much to our surprise, we are told that life is knowledge. This means first of all that life is relationship. No one has life from himself and only for himself. We have it from others and in a relationship with others. If it is a relationship in truth and love, a giving and receiving, it gives fullness to life and makes it beautiful. But for that very reason, the destruction of that relationship by death can be especially painful, it can put life itself in question. Only a relationship with the One who is himself Life can preserve my life beyond the floodwaters of death, can bring me through them alive. Already in Greek philosophy we encounter the idea that man can find eternal life if he clings to what is indestructible – to truth, which is eternal. He needs, as it were, to be full of truth in order to bear within himself the stuff of eternity. But only if truth is a Person, can it lead me through the night of death. We cling to God – to Jesus Christ the Risen One. And thus we are led by the One who is himself Life. In this relationship we too live by passing through death, since we are not forsaken by the One who is himself Life.
But let us return to Jesus’s words – this is eternal life: that they know you and the One whom you have sent. Knowledge of God becomes eternal life. Clearly "knowledge" here means something more than mere factual knowledge, as, for example, when we know that a famous person has died or a discovery was made. Knowing, in the language of sacred Scripture, is an interior becoming one with the other. Knowing God, knowing Christ, always means loving him, becoming, in a sense, one with him by virtue of that knowledge and love. Our life becomes authentic and true life, and thus eternal life, when we know the One who is the source of all being and all life. And so Jesus’ words become a summons: let us become friends of Jesus, let us try to know him all the more! Let us live in dialogue with him! Let us learn from him how to live aright, let us be his witnesses! Then we become people who love and then we act aright. Then we are truly alive.
 Twice in the course of the priestly prayer Jesus speaks of revealing God’s name. "I have made your name known to those whom you gave me from the world" (v. 6). "I have made your name known to them, and I will make it known, so that the love with which you have loved me may be in them, and I in them" (v. 26). The Lord is alluding here to the scene of the burning bush, when God, at Moses’ request, had revealed his name. Jesus thus means to say that he is bringing to fulfilment what began with the burning bush; that in him God, who had made himself known to Moses, now reveals himself fully. [Don't forget GS 22.] And that in doing so he brings about reconciliation; that the love with which God loves his Son in the mystery of the Trinity now draws men and women into this divine circle of love. But what, more precisely, does it mean to say that the revelation made from the burning bush is finally brought to completion, fully attains its purpose? The essence of what took place on Mount Horeb was not the mysterious word, the "name" which God had revealed to Moses, as a kind of mark of identification. To give one’s name means to enter into relationship with another. The revelation of the divine name, then, means that God, infinite and self-subsistent, enters into the network of human relationships; that he comes out of himself, so to speak, and becomes one of us, present among us and for us. Consequently, Israel saw in the name of God not merely a word steeped in mystery, but an affirmation that God is with us. According to sacred Scripture, the Temple is the dwelling-place of God’s name. God is not confined within any earthly space; he remains infinitely above and beyond the world. Yet in the Temple he is present for us as the One who can be called – as the One who wills to be with us. This desire of God to be with his people comes to completion in the incarnation of the Son. Here what began at the burning bush is truly brought to completion: God, as a Man, is able to be called by us and he is close to us. He is one of us, yet he remains the eternal and infinite God. His love comes forth, so to speak, from himself and enters into our midst. The mystery of the Eucharist, the presence of the Lord under the appearances of bread and wine, is the highest and most sublime way in which this new mode of God’s being-with-us takes shape. "Truly you are a God who is hidden, O God of Israel", the prophet Isaiah had prayed (45:15). This never ceases to be true. But we can also say: Truly you are a God who is close, you are a God-with-us. You have revealed your mystery to us, you have shown your face to us. You have revealed yourself and given yourself into our hands… At this hour joy and gratitude must fill us, because God has shown himself, because he, infinite and beyond the grasp of our reason, is the God who is close to us, who loves us, and whom we can know and love.
The best-known petition of the priestly prayer is the petition for the unity of the disciples, now and yet to come:  "I do not ask only on behalf of these – the community of the disciples gathered in the Upper Room – but also on behalf of those who will believe in me through their word, that they may all be one. As you, Father, are in me, and I am in you, may they also be in us, so that the world may believe that you have sent me" (v. 20ff.; cf. vv. 11 and 13). What exactly is the Lord asking for? First, he prays for his disciples, present and future. He peers into the distance of future history. He sees the dangers there and he commends this community to the heart of the Father. He prays to the Father for the Church and for her unity. It has been said that in the Gospel of John the Church is not present. Yet here she appears in her essential features: as the community of disciples who through the apostolic preaching believe in Jesus Christ and thus become one. Jesus prays for the Church to be one and apostolic. This prayer, then, is properly speaking an act which founds the Church. [!] The Lord prays to the Father for the Church. She is born of the prayer of Jesus and through the preaching of the Apostles, who make known God’s name and introduce men and women into the fellowship of love with God. Jesus thus prays that the preaching of the disciples will continue for all time, that it will gather together men and women who know God and the one he has sent, his Son Jesus Christ. He prays that men and women may be led to faith and, through faith, to love. He asks the Father that these believers "be in us" (v. 21); that they will live, in other words, in interior communion with God and Jesus Christ, and that this inward being in communion with God may give rise to visible unity. Twice the Lord says that this unity should make the world believe in the mission of Jesus. It must thus be a unity which can be seen – a unity which so transcends ordinary human possibilities as to become a sign before the world and to authenticate the mission of Jesus Christ. Jesus’ prayer gives us the assurance that the preaching of the Apostles will never fail throughout history; that it will always awaken faith and gather men and women into unity – into a unity which becomes a testimony to the mission of Jesus Christ. But this prayer also challenges us to a constant examination of conscience. [!] At this hour the Lord is asking us: are you living, through faith, in fellowship with me and thus in fellowship with God? Or are you rather living for yourself, and thus apart from faith? And are you not thus guilty of the inconsistency which obscures my mission in the world and prevents men and women from encountering God’s love? It was part of the historical Passion of Jesus, and remains part of his ongoing Passion throughout history, that he saw, and even now continues to see, all that threatens and destroys unity. As we meditate on the Passion of the Lord, let us also feel Jesus’ pain at the way that we contradict his prayer, that we resist his love, that we oppose the unity which should bear witness before the world to his mission.
At this hour, when the Lord in the most holy Eucharist gives himself, his body and his blood, into our hands and into our hearts, let us be moved by his prayer. Let us enter into his prayer and thus beseech him: Lord, grant us faith in you, who are one with the Father in the Holy Spirit. Grant that we may live in your love and thus become one, as you are one with the Father, so that the world may believe. Amen.