"We teach and define that it is a dogma divinely revealed: that the Roman pontiff, when he speaks ex cathedra, that is, when in discharge of the office of pastor and doctor of all Christians, by virtue of his supreme apostolic authority he defines a doctrine regarding faith or morals to be held by the universal Church, by the divine assistance promised him in blessed Peter, is possessed of that infallibility with which the divine Redeemer willed that his Church should be endowed for defining doctrine regarding faith and morals; and that therefore such definitions of the Roman pontiff are irreformable of themselves, and not from the consent of the Church."