Thus it is that Pope Innocent III states [De Consuetudine] that, it is necessary to obey the Pope in all things as long as he, himself, does not go against the universal customs of the Church, but should he go against the universal customs of the Church, 'he need not be followed' . . .

For who does not know, or does not advert to the fact, that what was given to the Roman Church by Peter, Prince of the Apostles, and is preserved even to this day, is what should be observed by all? Nor should anything be added, or anything unauthorized be introduced, nor should an exemplar be looked for elsewhere.