Page "First Vatican Council" Paragraph 6

The dogmatic constitution states that the Pope has " full and supreme power of jurisdiction over the whole Church " ( chapter 3: 9 ); and that, when he " speaks ex cathedra, that is, when, in the exercise of his office as shepherd and teacher of all Christians, in virtue of his supreme apostolic authority, he defines a doctrine concerning faith or morals to be held by the whole Church, he possesses, by the divine assistance promised to him in blessed Peter, that infallibility which the divine Redeemer willed his Church to enjoy in defining doctrine concerning faith or morals " ( chapter 4: 9 ).