Today, looking for things about the Sanctus, I ran across this, which priests could incorporate into an examination of conscience:
From Book VI On the priesthood by St. John Chrysostom. My emphases:
4. […] What manner of man ought [the priest] to be? For my part I think that the boldness of speech of Moses and Elias, is insufficient for such supplication. For as though he were entrusted with the whole world and were himself the father of all men, he draws near to God, beseeching that wars may be extinguished everywhere, that tumults may be quelled; asking for peace and plenty, and a swift deliverance from all the ills that beset each one, publicly and privately; and he ought as much to excel in every respect all those on whose behalf he prays, as rulers should excel their subjects.
And whenever he invokes the Holy Spirit, and offers the most dread sacrifice, and constantly handles the common Lord of all, tell me what rank shall we give him? What great purity and what real piety must we demand of him? For consider what manner of hands they ought to be which minister in these things, and of what kind his tongue which utters such words, “And we pray and beseech Thee, send down thy Holy Ghost upon us and upon these gifts here outspread, and make this bread to be the precious body of thy Christ, and that which is in the cup the precious blood of Christ, having so changed them by thy Holy Spirit that to us who partake of them they may be for the cleansing of our souls, the remission of sins, the communion of the Holy Spirit.” [Liturgy of St. Chrysostom.] and ought not the soul which receives so great a spirit to be purer and holier than anything in the world? At such a time angels stand by the Priest; and the whole sanctuary, and the space round about the altar, is filled with the powers of heaven, in honor of Him who lieth thereon. For this, indeed, is capable of being proved from the very rites which are being then celebrated. I myself, moreover, have heard some one once relate, that a certain aged, venerable man, accustomed to see revelations, used to tell him, that he being thought worthy of a vision of this kind, at such a time, saw, on a sudden, so far as was possible for him, a multitude of angels, clothed in shining robes, and encircling the altar, and bending down, as one might see soldiers in the presence of their King, and for my part I believe it. […] And dost thou not yet tremble to introduce a soul into so sacred a mystery of this kind, and to advance to the dignity of the Priesthood, one robed in filthy raiment, whom Christ has shut out from the rest of the band of guests [Matthew 23:13]. [My Jesus, mercy.] The soul of the Priest should shine like a light beaming over the whole world. But mine has so great darkness overhanging it, because of my evil conscience, as to be always cast down and never able to look up with confidence to its Lord. Priests are the salt of the earth.