The Eucharist

The Eucharist is the heart of Christian prayer, and for centuries Catholic monastics have celebrated Mass daily. It is a commemoration of the death and resurrection of Jesus Christ, who loved us so much that he gave his own body and blood for our redemption. In the Eucharist the Word of God is proclaimed, and bread and wine become the body and blood of Christ, given to us to eat and drink. We experience the Eucharist as something so profound, and so filled with love, that it goes beyond the power of words to express. Just as prayer is to our spirits what breath is to our body, so the Eucharist is in every way the deepest nourishment of our souls, food and drink indeed. Above all, it is a foretaste of the heavenly banquet where we hope one day to eat and drink with our Lord and all his saints. And as we drink, our thirst for heaven is "not quenched but kindled."

The first generation of Christians experienced such profound gratitude toward God for their new life in Christ that they named this meal in which his body and blood are consumed the "Eucharist" from the Greek eucharistein, "to thank." As we celebrate God's love our minds are turned away from the sadness and complaining to which the human heart is so prone, toward living with a deep spirit of constant gratitude for all God's gifts, especially for the love he has poured out for us in Christ Jesus. 

So precious is this mystery that some of the bread consecrated during the Mass (the "Blessed Sacrament") is kept in a tabernacle, a box fixed in a prominent location in our church, to be with us all the day. Whenever we enter our church we are conscious of the presence of Christ who has given himself to us in every way possible, even to becoming our food, and we are filled with reverence and awe.

Exposition and Benediction   

During the Middle Ages a practice arose of sometimes taking the wafer of consecrated bread out of the tabernacle, placing it in a vessel designed to make it visible to as many people as possible, and leaving it "exposed" to view for a while hence the name of this devotion, "Exposition." Those present at Exposition join together in silently adoring Christ present in the consecrated bread. When a priest is present, at the end of Exposition he may bless those present, taking the vessel with the Sacrament in both hands and making the sign of the cross over the people with it. This is called "Benediction" from the Latin word benedicere, "to bless".  

links:

Monachos.net - Orthodoxy through Patristic, Monastic and Liturgical Study

The Center For Liturgy at St Louis University - readings and resources for Sunday Eucharist