A rubric in the Roman Missal notes that three principal mysteries are commemorated in this Mass and should be explained in the homily:
the institution of the Eucharist;
the institution of the priesthood;
and Christ’s commandment of brotherly love.
The first is covered by the first and second readings; the second, by the gospel; the third is implicit in all three readings. The readings are the same every year.
Although it is much disputed whether the Last Supper was a Passover (so the Synoptic Gospels) or a meal preceding the Passover by twenty-four hours (so John), two things are certain: the original meal of Jesus and his disciples was undoubtedly surrounded by Passover associations, and the accounts of the institution have been impregnated with paschal theology, both in Paul (see the second reading) and in the Synoptists.
Preeminently, too, the Israelite Passover provided the background for the annual Christian feast, and therefore most especially for the Easter Eucharist at the conclusion of the vigil. It is therefore doubly fitting that the Triduum should begin with this reading.
Three points may be made here. (1) The Passover is an (annual) memorial of the great redemptive act of God that constituted God’s first people. “Memorial” means more than mentally recalling. The devout Jew believed that at the celebration of Passover he or she was actually coming out of Egypt with his or her ancestors. The same realism colors the Christian Eucharist and preeminently the Triduum.
(2) The shedding of the blood of the lamb provided an obvious type for the death of the Lamb of God, who takes away the sin of the world. For the Christian dispensation, the bloodshedding is more than a ritual or cultic act—it is a moral act (Heb 10:5-10) that becomes an event of salvation history. It is the making present of this event that is one of the main meanings of the Eucharist.
(3) The Passover (meal) was eaten in great haste and expectation. In the course of centuries, this sense of urgency was transformed into an expectation of the Messiah, who was to come that night. The early Christians likewise began their Passover celebration looking for the coming of Christ, and even when the Second Coming did not occur, they believed that he came in the Easter Eucharist in anticipation of his final coming (Marana tha!).
This psalm underlines two aspects of the Eucharist: the sacrifice of thanksgiving and the communion among believers, a sharing of the cup. Some traditions have overemphasized the one to the exclusion of the other. The Eucharist is both together.
This is one of the earliest fragments of Christian tradition preserved in the New Testament (see also 1 Cor 15:3-7). Paul says that he “received” it before he “handed it on” to the Corinthians about 50 C.E., and the words for “receive” and “hand on” represent words for the passing on of tradition as in rabbinic practice.
So we are dealing here, not with a vision “received from the Lord,” but with a tradition handed down through human witnesses, though always under the supervision of the exalted Christ.
This is not a complete description of the Last Supper but a liturgically stylized account, selecting and interpreting those features of the meal that were of importance for the Christian Eucharist.
Its mention of the supper between the bread and the cup indicates its primitive character. Only Paul and the long text of Luke mention the command to repeat it in memory of Christ, but the other accounts presume this by their very existence, for they were recorded precisely because the church was “doing this” as a memorial of the Lord.
Paul also preserves what is more prominent in the Synoptic accounts, the anticipation of the Second Coming. In Paul, as in the Synoptists, the Eucharist looks both backward and forward—backward to the redemptive event of the Cross here made present, and forward to the Second Coming here anticipated.
The theme of brotherly love is introduced at the footwashing, as the Lord says: “I have set you an example, that you also should do as I have done to you” (13:15). This example is further defined later in the discourse, after the supper: “I give you a new commandment: that you love one another just as I have loved you” (Jn 13:34, the versicle before the Gospel; the Latin mandatum gave this day its traditional English name of Maundy Thursday).
Modern exegetes find two themes in the footwashing, the first symbolic, the second exemplary. The symbolic meaning asserts that Jesus lays aside his garments as a parable of humiliation. He stooped, first to become incarnate, then to die in order to cleanse humankind of sin; finally he returns in glory to the Father.
The whole incident is an acted parable of the Carmen Christi (see the Second Reading of Passion Sunday). The symbolic meaning is expressed in verse 3: “Jesus, knowing that the Father had given all things into his hands, and that he had come from God and was going to God. ... ”
The exemplary meaning is expressed in verse 15: “For I have set you an example, that you also should do as I have done to you.”