XII. Or to put the argument somewhat differently, thus: As the existence of causes is deduced, _a posteriori_, from effects, so it is perfectly established, _a priori_, whenever the series and sum of effects, of which the senses are cognisant, are foretold from it with certainty. We deduce the force of gravity necessarily from its effects, a posteriori, but we likewise determine it to exist, with a judgment no less invariable, a priori, when it is such that we do not merely guess at, but certainly anticipate, its sensible effects. Now Peter's supremacy is not inaptly compared with this very force of gravity. For it is a characteristic of each to be, in its proper order of things, the source and principle in which effects are involved, which afterwards become apparent, whether in this physical universe, or in the supernatural region of the Church. Suppose, then, Peter to have held the dignity which we claim for him. What happens in the Acts which might not, nay, which should not, have been anticipated? Is it his being mentioned above all, his speaking in the name of all, his constantly taking the lead, and his eminence, as if he were the head? But it could not be otherwise if he alone received from Christ a higher dignity than all the rest. Is it his discharging the office of supreme Judge, Legislator, Teacher, and Doctor? Is not this just what was to be expected from the rank of Head and universal Pastor? The Primacy, then, the larger authority, and the unshared majesty of Peter, belong to that class of truths which are indubitably believed on the strength of deduction, and rational anticipation. Having noted, if not all, at least the greater number of those arguments which we have alleged hitherto in favour of our cause, we approach the question which was secondly to be cleared up, what, namely, is _the force and nature of that Primacy_, which the same arguments prove to belong to Peter. For I know that all Protestants are possessed with the notion that no other pre-eminence should be ascribed to Peter, on scriptural authority, than one limited to a certain precedency of honour and order. That _precedency_ should be granted Peter they are not unwilling to admit, but _supremacy_, they stoutly maintain, must not and cannot be allowed him. As to which their opinion I consider, that it would be much the shorter way to strip Peter utterly of every prerogative, than to attenuate the distinctions applied to him in Scripture to a sort of shadowy precedency. I consider that nothing is so foreign to truth and the Scriptures, as on their testimony to allow that Peter was distinguished from the rest of the Apostles, but to confine that superiority within the very narrow bounds of honour and order.