There are already, within the reach of all, standard -works upon the Divine Institution or the Papal Supremacy. The same can not be said of the several prerogative, consequent on the Supremacy. And yet, in these unstable times, when the eyes of the whole world are directed toward the Holy See, as toward the only safeguard and stronghold, not merely of the Church, but even of Christianity, it were desirable to have at hand able treatises, setting forth, in detail, the rights vested exclusively in the Sovereign Pontiff. Now, among these, none is capable of eliciting a more intense interest than his Apostolic Authority, as the divinely commissioned teacher of the Church. We thought, therefore, that we should meet a general want, by submitting to the public the present unpretentious volume, in which it has been our humble aim to collect an invincible attay of arguments in support of the point in question.