Who and what are we offering at Mass?

When ... the bread and the wine are placed on the altar we are symbolically hidden in them, united to Jesus Christ and offered with him. (Blessed Columba Marmion, Christ: the Ideal of the Priest, Ignatius Press, p.217)

So when the priest says the following prayer at the Offertory:

Suscipe, sancte Pater, omnipotens ætérne Deus, hanc immaculátam hóstiam, quam ego indígnus fámulus tuus óffero tibi Deo meo vivo et vero, pro innumerabílibus peccátis, et offensiónibus, et neglegéntiis meis, et pro ómnibus circumstántibus, sed et pro ómnibus fidélibus christiánis vivis atque defúnctis: ut mihi, et illis profíciat ad salútem in vitam ætérnam. Amen.

Receive, O holy Father, almighty and eternal God, this spotless host, which I, Thy unworthy servant, offer unto Thee, my living and true God, for mine own countless sins, offenses and negligences, and for all here present; as also for all faithful Christians living and dead, that it may avail both for my own and their salvation unto life eternal. Amen.

what is the "immaculate (or spotless) host"? Is it the bread that lies on the altar? Maybe. But surely it is also the Church, all of us. The Church is spotless, we no doubt are sinners, and yet we are all that the Son has to offer to the Father. The priest, standing in persona Christi, professes the fact that he is servant and unworthy, that he has countless sins that require the Father's mercy. In some senses, he is Christ taking upon Himself all the sins of the Church so that the Church can be offered pure and spotless.

I am reminded of the first time I celebrated Mass in the Extraordinary Form. Even though I had read and rehearsed the prayers, it was only when standing at the altar that the force of the following words said in preparation for Holy Communion after the Lord's Prayer became apparent to me:

Domine Jesu Christe, qui dixisti Apostolis tuis: Pacem relinquo vobis, pacem meam do vobis: ne respicias peccata mea, sed fidem Ecclesia tua; eamque secundum voluntatem tuam pacificare et coadunare digneris: Qui vivis et regnas Deus per omnia saecula saculorum. Amen.

O Lord Jesus Christ, who saidst to Thy Apostles, Peace I leave with you, My peace I give unto you; look not upon my sins, but upon the faith of Thy Church; and vouchsafe to grant her peace and unity according to Thy will: O God who livest and reignest world without end. Amen.

The faith of the Church is pleasing to God, even if the priest is sinful and unworthy. Even though the Mass is effective even if the participation of the faithful is lacking, think dear Catholic faithful of how the priest asks the Father to look upon your faith and upon you as members of the immaculate Bride of Christ, a spotless victim offered to the Father in union with His Son.

Pray for me as I go now to offer the Holy Sacrifice. I'll make a special memento for all my readers.