"The Church tolerates hymns when necessary, but hymns at the processional parts of Mass begin in history with a merely human author, and so lack the liturgical dance with time that is liturgical sacrifice. (I should also add that the Church is a pilgrim in procession to our future, and never processes back in time. So there is no procession at the end of Mass, and, therefore, no chant at the end of Mass. We can sing a song at the end of Mass, or recite a devotional prayer, but these are not liturgical; they are not part of the Mass.)
When we understand that the Holy Mass comes to us from our future, we begin to understand that there are no separate Masses: Thursday Mass, Sunday Mass, Requiem Mass, etc. Neither is the Mass weighted in the past, as is the Passover observance of the Jews, in which they truly step back into the past event of their salvation from slavery to man. Ours is a salvation from ourselves, and so finds its final effect only in the future, when we leave the world of time as we know it, passing through death and purgation, perhaps, into the Promised Land.
When we realize that this is all a little beyond our comprehension, and certainly beyond our usual experience of reality, we begin the procession into the mystery of the Mass, and start to participate fully, consciously, and actively in the mystery. And we can understand that the priest can pray, in thanksgiving for a prayer that’s already been answered, that the Father bless, acknowledge, and approve our offering bread and wine in every respect, only because the Father already accepts the Lamb in our future."