During the evening of Holy Thursday, the Mass of the Lord's Supper is celebrated. It is celebrated in the evening because the Passover began at sundown. There is only one Mass, at which the whole community and priests of the parish participate. This is a very joyful Mass, as we recall the institution of the Holy Eucharist and the priesthood. The priests wear white vestments, the altar is filled with flowers, the Gloria is sung and the bells are rung. After the Gloria, we shall not hear organ music and the bells until the Easter Vigil. The Liturgy of the Mass recalls the Passover, the Last Supper, which includes the Washing of the Feet. The hymn Ubi Caritas or Where Charity and Love Prevail is usually sung at this time. After the Communion Prayer, there is no final blessing. The Holy Eucharist is carried in procession through Church and then transferred into a place of reposition, usually a side chapel. The hymn Pange Lingua is also usually sung at this time. 
When the Eucharist is processed to the altar of repose after the Mass of the Lord's Supper, we should remain in quiet prayer and adoration, keeping Christ company. There is a tradition, particularly in big cities with many parishes, to try and visit seven churches and their altar of repose during this evening. 
In imitation of Christ's last supper, many Christians prepare a seder meal or the pasch. Celebrating a paschal meal helps us comprehend the plan of redemption. We see the lamb, cooked whole, with no bones broken, foreshadowing the death of Christ, the Lamb of God. We eat the unleavened bread and recall to mind the Eucharist. We eat the whole meal in prayerful reminder of that Last Supper that Jesus spent with His apostles, His friends, instituting Holy Orders and leaving His greatest gift, the Holy Eucharist. 
This is my body that is for you. Do this in remembrance of me. (1 Corinthians 11:24)
Today we celebrate Holy Thursday, the day when Jesus instituted the Eucharist and told us, “Do this in memory of me.” Since that day, Mass has been celebrated hundreds of millions of times in every corner of the world—all in obedience to Jesus’ command.
There is an intimate relationship between what happened on Holy Thursday and what happened on Good Friday—and that relationship applies to us today. On the cross, Jesus gave up his life for our sins and reconciled us with his Father. But his death on the cross doesn’t mean that we go to heaven automatically. We need to cooperate with the grace that he poured out on the cross. And this is where the Eucharist comes in.
The Jesus who died on the cross is the same Jesus who is now present on the altar at Mass. The One who paid for our sins on the cross is the same One who freely pours out the blessings and grace of our redemption on the altar. The One who said, “Father, into your hands I commend my spirit” on the cross now offers himself to us—body and blood, soul and divinity—in the form of bread and wine.
On the cross, Jesus offered a perfect sacrifice that never needs to be repeated. On the altar, that once-for-all sacrifice is made present to us again so that we can marvel at our redemption. On the cross, he took away our sins. On the altar, he offers us continued strength to overcome the pull of sin and enter into his presence more fully. In effect, the work of the cross continues on the altar. That’s how committed Jesus is to bringing us fully into his kingdom!
So when you go to Mass today, be sure to lift up your heart to the Lord. Look intently at the consecrated Host, and see Jesus there before you. See him pouring out his mercy. See him pouring out his love. He is there, at every Mass, always working to draw us closer to himself.
“Jesus, I am in awe of your redemption. Open my eyes, Lord, to see you on the altar today and every day. Lord, I give you my heart.”
Exodus 12:1-8, 11-14; Psalm 116:12-13, 15-18; John 13:1-15
