[T]he divine Redeemer has so willed it that the priestly life begun with the supplication and sacrifice of His mortal body should continue without intermission down the ages in His Mystical Body which is the Church. That is why He established a visible priesthood to offer everywhere the clean oblation which would enable men from East to West, freed from the shackles of sin, to offer God that unconstrained and voluntary homage which their conscience dictates.
3. In obedience, therefore, to her Founder's behest, the Church prolongs the priestly mission of Jesus Christ mainly by means of the sacred liturgy. She does this in the first place at the altar, where constantly the sacrifice of the cross is represented and with a single difference in the manner of its offering, renewed. She does it next by means of the sacraments, those special channels through which men are made partakers in the supernatural life. She does it, finally, by offering to God, all Good and Great, the daily tribute of her prayer of praise. "What a spectacle for heaven and earth," observes Our predecessor of happy memory, Pius XI, "is not the Church at prayer! For centuries without interruption, from midnight to midnight, the divine psalmody of the inspired canticles is repeated on earth; there is no hour of the day that is not hallowed by its special liturgy; there is no state of human life that has not its part in the thanksgiving, praise, supplication and reparation of this common prayer of the Mystical Body of Christ which is His Church!"
4. Cf. Mal.1:11.
5. Cf. Council of Trent Sess. 22, c. 1.
6. Cf. ibid., c. 2.
7. Encyclical Letter Caritate Christi, May 3, 1932.