Our Mother of Sorrows Parish in Tucson shared an explanation of the liturgy in the church's Oct. 11 bulletin. 

"We left off last week having acknowledged our sins in the Rite of Penitence which continues with the prayer for mercy, Kyrie Eleison, which means 'Lord have mercy,'" Deacon Scott Thrall said in the bulletin. "The Kyrie, which is both a prayer for mercy and an admission of sin, reminds us of Psalm 51, which begins: 'Have mercy on me, O God.'" 

Next, he explained the origin of the words Amen, Alleluia and Hosanna, which are all ancient expressions that have been retained in the Mass. 

"The Mass has been celebrated in many different countries, in different languages, over two thousands years; these Greek and Hebrew words echo its earliest origins," Thrall said.

The acclamation of praise reminds us of when Christ was born and the angels and the multitude of the heavenly host sang praises to God. 

"The final 'Amen' affirms our commitment to God as His people," Thrall said. 

The opening prayer, known as the Collect, is a collection of prayers for the day; and the opening prayer serves as a way to set the tone of the entire Mass. 

We pray "to the Father, through the Son, in the power of the Holy Spirit, to unite our prayers with Christ's own prayer to His Heavenly Father," Thrall said. "These prayers of the Introductory Rite form a kind of crescendo, whereby we are brought from a sinful world into the presence of God and prepared to approach Him, so as to hear His Word and to participate in the Sacrament of Holy Eucharist."

For more information on the Mass, Dcn. Thrall recommended purchasing and reading the book "The Lamb's Supper: The Mass as Heaven on Earth" by Scott Hahn.