The Eucharist makes present in space and time the actions of the eternal Son of God done almost twenty centuries ago in a specific culture and time. Therefore, we are bound to certain specifics in our celebration of his mysteries. For instance, Jesus used unleavened bread and grape wine at the Last Supper.
So we also use unleavened bread and grape wine as the elements which are transformed by the action of Christ himself into his Body and Blood.
It is certainly true that the Church has changed some
aspects of the rituals celebrating the sacraments down through the centuries. One such series of changes took place after the Second Vatican Council, although there have been many changes throughout the history of the Church. However, the essence of the sacraments, established by Christ, does not change.
The liturgy is a vital source of the unity of the Church.
Therefore, only the supreme authority of the Church (the Pope), under the guidance of the Holy Spirit promised by Jesus, may establish liturgical changes. The Church herself provides options for variations within the rituals. These options may be chosen at the discretion of the celebrant, again with the purpose of assisting a particular congregation to celebrate the mysteries of Christ more fully.
The liturgy is the solemn repetition of what Jesus Himself has done for our salvation. So liturgical change is never done just for the sake of novelty or variety. Rather, it is undertaken carefully in order to make the timeless mysteries of Christ more accessible and understandable in the changing conditions of human history and cultures, and is revisited periodically to adapt to circumstances.
This is always aimed at fostering the unity for which Jesus prayed at the Last Supper (John 17:21). In other words, the ritual of the celebration can be changed by the authority of the Church to help people appreciate the essence of what is being celebrated.
As noted previously, salvation history as well as the life of the Church culminate in the Eucharist. The Eucharist is truly Jesus Christ himself, present in his Body and Blood, soul and divinity. Through the ministry of the priests of the new covenant, empowered by him sacramentally to celebrate his mysteries, the one perfect and all-sufficient sacrifice of the Cross is made present in the created world throughout space and time. It is an abiding consolation for us on our pilgrim journey, giving us strength to persevere in faith, hope and charity on our pilgrimage of faith. This pilgrimage is the final Passover of the Church to the promised land of heaven, where one day we hope to meet the Lord face to face (I Corinthians 13:12). Preparing for the Great Jubilee of the year 2000, Saint John Paul wrote (Ecclesia de Eucharistia, n. 20):
The Eucharist is truly a glimpse of heaven appearing on earth. It is a glorious ray of the heavenly Jerusalem which pierces the clouds of our history and lights up our journey … it spurs us on our journey through history and plants a seed of living hope in our daily commitment to the work before us. Certainly the Christian vision leads to the expectation of “new heavens” and “a new earth” (Rev 21:1), but this increases, rather than lessens, our sense of responsibility for the world today. I wish to reaffirm this forcefully at the beginning of the new millennium, so that Christians will feel more obliged than ever not to neglect their duties as citizens in this world. Theirs is the task of contributing with the light of the Gospel to the building of a more human world, a world fully in harmony with God's plan.