From the above every one will readily understand what there is in that oft quoted saying of Gregory's[80]: "A mass celebrated by a wicked priest is not to be considered of less effect than one celebrated by any godly priest, and St. Peter's mass would not have been better than Judas the traitor's, if they had offered the sacrifice of the mass." Which saying has served many as a cloak to cover their godless doings, and because of it they have invented the distinction between _opus operati_ and _opus operantis_[81], so as to be free to lead wicked lives themselves and yet to benefit other men. But Gregory speaks truth; only they misunderstand and pervert his words. For it is true beyond a question, that the testament or sacrament is given and received through the ministration of wicked priests no less completely than through the ministration of the most saintly. For who has any doubt that the Gospel is preached by the ungodly? Now the mass is part of the Gospel, nay, its sum and substance; for what is the whole Gospel but the good tidings of the forgiveness of sins? But whatever can be said of the forgiveness of sins and the mercy of God, is all briefly comprehended in the word of this testament. Wherefore the popular sermons ought to be naught else than expositions of the mass, that is, a setting forth of the divine promise of this testament; that would be to teach faith and truly to edify the Church. But in our day the expounders of the mass play with the allegories of human rites and play the fool with the people.