"Marriage is not a union merely between two creatures - it is a union between two spirits; and the intention of that bond is to perfect the nature of both."

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Therefore, if the earthly power errs, it shall be judged by the spiritual power ... but if the supreme spiritual power errs it can be judged only by God, and not by man ... Therefore we declare, state, define and pronounce that it is altogether necessary to salvation for every human creature to be subject to the Roman pontiff.

— Pope Boniface VIII