An apostolic letter to the bishops, priests, deacons, consecrated persons and lay faithful on the liturgical formation of the People of God, offered as a reflection rather than as new legislation after Traditionis Custodes. Taking its title from Christ's words at the Last Supper, it presents the liturgy as the place of encounter with the risen Lord, insists that the Council's liturgical reform is irreversible, and diagnoses the real problem as a lack of formation. It distinguishes formation for the liturgy from formation by the liturgy, treats the recovery of a capacity for symbols and for silence, and gives careful attention to the ars celebrandi.