I believe that the importance of this point of doctrine, its religious significance, is very significant... How can man, earthbound and sinful as he is, succeed in reaching the throne of God? And then the miracle occurs, God himself takes our place and fulfills the sacrifice. Even before this happened we could offer him only what we had already received from him, somewhat in the way children can only celebrate their parents' birthdays by offering flowers gathered from their father's garden, or a present bought with money from their mother's purse. But what we are now considering is something much greater than this. Through transubstantiation, our humble offering is transformed into that of Christ, whilst still remaining our own, or rather that of the Church; this is why after the consecration, the liturgy continues to speak of the elements on the altar as our gifts and also as the offered body and blood of Christ. Ultimately it is always a question of that admirabile commercium, that wonderful exchange and intercourse, hymned in the Christmas liturgy, and of that principle in which the Fathers sum up God's whole purpose: He became man in order that we might become God! Our offering, and ourselves in and through it, can travel all the distance to God, because it has been transformed into the supremely holy and effective offering of Jesus Christ, which, in this way, retains its autonomy and yet is extended to his mystical Body.

The Real Presence Through the Ages
Fr. Michael L. Gaudoin-Parker