The Catholic Church strongly believes that after the words of consecration said by a priest at Mass, by the
power of the Holy Spirit, bread and wine are being transformed into the body, blood, soul and divinity of Jesus Christ.
Indeed, this is a great mystery, one that has been handed down to us from Jesus Christ at the Last Supper.
According to the Roman Rite of the Catholic Church, it is a custom that during the Eucharistic prayer to elevate the consecrated Host as well as the chalice holding the precious Blood, lifting them up to the eyes of the people.
As this action of the priest is often not long, the faithful are encouraged to make a silent act of love to God. But some spiritual writers suggest that we use the words of St. Thomas the Apostle when he encountered the risen Christ, as the priest elevates the Host.
“My Lord and my God!” (John 20:28)
Traditional, it is to pray silently, when the Chalice is elevated,
“My Jesus, mercy!”
This is a way to express your own belief that truly, God is present, overcoming any doubts you may have, similar to what St. Thomas experienced.
Though, other spiritual books will offer more lengthy prayers, like the following two prayers from the St. Vincent Manual which is published in 1856.
Hail, Victim of salvation! Eternal King! Incarnate Word, sacrificed for me and all mankind! Hail, precious Body of the Son of God! Hail, sacred flesh, torn with nails, pierced with a spear, and bleeding on a cross, for us poor sinners!
O amazing goodness O infinite love! Oh! let that tender love plead now in my behalf! Let all my iniquities be here removed, and my name be written in the book of life! I believe in you; I hope in you; I love you. To you be honor, praise and glory from all creatures for ever.
Hail, sacred blood, which flows from the wounds of Jesus Christ, and washing away the sins of the world! Please, Cleanse, sanctify and preserve my soul, that nothing may separate me from you! Behold, O eternal Father! Your holy Jesus, and look upon the face of thy Christ, in whom thou art well pleased.
Hear the voice of his blood, that cries out to thee, not for vengeance, but for pardon and mercy. Accept this divine oblation, and through the infinite merits of all that Jesus endured on the cross for our salvation, be pleased to look upon us, and upon all thy people, with an eye of mercy.
But in either way, whatever you do during the consecration at Mass, look up and see the Risen Lord and give to him both your love and adoration.
He comes during every Mass for you and He desires to dwell in your heart.