The “theme” of the liturgy on MAUNDAY THURSDAY is not the institution of the Eucharist but the whole Paschal Mystery, similarly to Good Friday or Easter Sunday. The classics of liturgical doctrine explained repeatedly that during these holy days our Passover celebration always recalled the memory of Christ’s Paschal mystery in its integrity. On a given day some aspects may gain prevalence above the others but always as part of the whole, in close connection with it. Even when viewed separately, the specific content of Maundy Thursday can be regarded as multi-layered combining various elements of the Last Supper, the Lord’s Last Sermon, his apprehension and interrogation (chronologically the first events of his Passion). The feelings vibrating in the soul of the Church correspond to the two sayings of the Lord: “With desire I have desired…” – and “Father, if you will…”
The reason why in the Middle Ages the Church felt the need to create the Feast of Corpus Domini is because she realized that Maundy Thursday was not the feast of the institution of the Eucharist. Maundy Thursday is a day of the celebration of the Paschal Mystery, a day of the celebration of the Passion, a day of presenting the Redemption through mysteries — and in this context and among other motives only — the remembrance of the institution of the Eucharist.
This complexity manifests itself within the Mass, too. The Introit (Nos autem gloriari), the Gradual (Christus factus est) and the Offertory (Dextera Domini) refer to the fundamental element of the celebration, i.e. the whole Paschal Mystery. The Gospel recalls the washing of the disciples’ feet, the original oration puts the motive of Judas’s betrayal into the context of the Holy Week as a whole. This statement will prove to be even more valid in view of the fact that the liturgy of Maundy Thursday was not confined to the celebration of the Mass. In the animate medieval liturgy the Mass was followed by a tremendous complexity of rites designated Mandatum (see: “Maundy” Thursday). In this rite the washing of feet, the cultic reading of the Last Sermon, the ritual meal (agape), the pious veneration of the altars were all combined to a homogenous sequence of events of dramatic nature. The whole was accompanied by a completely matching set of texts and chants. Besides, we have to mention the ceremony of the “Reconciliation of Penitents” taking place in the morning of this day It had survived in some religious orders as a rite of purification up to the recent past closing down the Lenten period and preparing the souls directly for Easter.
Laszlo Dobszay, The Bugnini-Liturgy and the Reform of the Reform (2003)