At the Last Supper the Lord himself directed his disciples' attention toward the fulfillment of the Passover in the kingdom of God: "I tell you I shall not drink again of this fruit of the vine until that day when I drink it new with you in my Father's kingdom." Whenever the Church celebrates the Eucharist she remembers this promise and turns her gaze "to him who is to come." In her prayer she calls for his coming: "Marana tha!" "Come, Lord Jesus!" "May your grace come and this world pass away!"
Source: Catechism of the Catholic Church (Vatican.va)