57 In this regard, We are pleased to repeat the words used by Our immediate predecessor of happy memory in the Apostolic Exhortation entitled Menti Nostrae : "Just as the whole life of Our Savior was pointed toward His sacrifice of Himself, so too the life of the priest, who must reproduce the image of Christ in himself, must become a pleasing sacrifice with Him and through Him and in Him. . . And so it is not enough for him to celebrate the Eucharistic sacrifice, but in a very deep sense, he must live it; for in this way, he can draw from it the heavenly strength that will enable him to be profoundly transformed and to share in the expiatory life of the Divine Redeemer himself. . . .(65) And again: "The soul of the priest must refer what takes place on the sacrificial altar to himself; for just as Jesus Christ immolates Himself, his minister must immolate himself along with Him; just as Jesus expiates the sins of men, so too the priest must tread the lofty path of Christian asceticism to bring about his own purification and that of his neighbors." (66)
Source: Sacerdotii Nostri Primordia (Vatican.va)