The truth would seem to be, that according to the Roman theory, a marriage prohibited by Scripture may yet be licensed by the Pope: because, according to the tenet of infallibility, it is only God Himself dispensing with His own positive law: as in the allowance of polygamy to the Patriarchs, in the sacrifice of Isaac, and in the direction given to marry the widow of a brother who had died childless.
Therefore, notwithstanding the practice of the modern Roman Church, and the opinion of some of its divines, we may not be far wrong in asserting, that the whole Church from the beginning, and certainly the whole undivided Church, is with us in both parts of our argument. It has considered the Levitical prohibitions as binding upon Christians, except so far as they are dispensed with by a sufficient (i.e. a Divine) authority: and it has considered the wife's sister as coming within those prohibitions.
Are we prepared, in the face of all this, to alter our Table of prohibited degrees? At least, let us distinctly understand what sort of