Mediator Dei §2

² But what is more, the 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.