Explanation of the Prayers and Ceremonies of Holy Mass, Dom Prosper Guéranger - Orate, Fratres

Then the Priest, having kissed the Altar, turns towards the people with this salutation: Orate, fratres, ut meum ac vestrum sacrificium acceptabile fiat apud Deum Patrem Omnipotentem.  These words form the Priest’s farewell to them, for he will not again turn to them, until the Sacrifice is consummated.  But, observe that this is not his ordinary parting word; as, for instance, when he went up to the Altar, his merely said Dominus vobiscum.  In this place, he recommends himself to the prayers of the Faithful, in order that this Sacrifice, which belongs, at once, both to Priest and people, may be pleasing unto God.  The Sacrifice is the Priest's, for he is the direct agent therein; the Sacrifice belongs to the Faithful, because Jesus Christ instituted it for their particular profit; see now why it is that the Priest lays such stress upon these words: meum ac vestrum sacrificium.  For the very same reason, likewise, he re-awakens the attention of the Faithful, urging them more and more to earnestness; for it behoves them not to forget, that they too have a share in the Priesthood, as says St. Peter, calling the Faithful a kingly Priesthood, regale sacerdotium (1 S. Peter ii. 9), by the mere fact that they are Christians.  They come from Christ, they belong to Christ, they have been anointed, and by their very baptism have become other Christs; needs must be, therefore, that they too hold the power of offering Sacrifice in union with the Priest. - Thus, aroused by the Priest’s voice, they hasten to respond to his desire, by giving expression to their own hearty wish: Suscipiat Dominus sacrificium de manibus tuis, ad laudem et gloriam nominis sui, ad utilitatem quoque nostram, totiusque Ecclesiae suae sanctae.  May the Lord receive this Sacrifice from thy hands, for the praise and glory of His name, for our own weal, and for that of His Holy Church.  The Missal still retains in a parenthesis, in this place, the word meis to suit an occasion in which the Priest himself might be obliged to supply for the absence or ignorance of the server of his Mass.

This response having been made by the Faithful, they should reflect how they will indeed see the Priest’s face no more, until the Lord Himself has come down on our Altar.  His voice even will not be heard again, save once; and that will be for the intoning of the great and magnificent Prayer of Thanksgiving. namely, the Preface.

But, before this, he collects the desires of the Faithful, into one Prayer, which, as he says it in an undertone, has received the name of the secret; for the same reason that he prays here in silence, he does not precede it with the usual word Oremus, Let us pray, inasmuch as he is not now convening the Faithful to make it with him.  In the Sacramentaries, that of St. Gregory, for example, this Prayer is entitled: Oratio super oblata.