What is this part of the Mass?
The Liturgy of the Eucharist begins with the Presentation and Preparation of the Gifts. The priest prepares the altar for sacrifice while the gifts of bread and wine are brought forward by lay members of the assembly. 

What do we say now and what is changing?
Next comes the Sanctus (SONK-toos) or Holy, Holy, Holy. It comes at a significant time in the Mass. The Sanctus is just before we ask the Holy Spirit to transform the bread and wine into the Body and Blood of Christ. This entire prayer is composed of words that come from Scripture. With it we directly address God and proclaim His majesty together with the angels. Every time we say or sing the Sanctus we join the angels and saints in their song, singing a perfect hymn of praise to a perfect and holy God.

Instead of beginning the Sanctus with “Holy, Holy, Holy Lord, God of power and might” we will instead say or sing (raise hands here): “Holy, Holy, Holy, Lord God of Hosts” which are the words that the prophet says he hears the angels singing in God’s presence in Isaiah 6:1-3. Lord God of Hosts is the title that the young David called God when he prepared to fight the giant Goliath in 1 Samuel 17:1-45. Holy, Holy Holy, is the cry of the heavenly host surrounding the throne of God in St. John’s vision of heaven in Revelation 4:8-10. In Hebrew, “hosts” refers to an army. It may refer to God’s protection of the armies of Israel, but it may also refer to the ‘armies’ of the heavenly king – that is, the angels, as well as the ‘hosts’ of saints in heaven.

This is the heavenly King who is about to descend in the Eucharist, with countless angelic hosts attending him. Here, we sing the theme song of the angels!