Pope St. Martin, Lateran Council, Can. 17: “If anyone in word and mind does not properly and truly confess according to the holy Fathers all even to the last portion that has been handed down and preached in the holy, Catholic, and apostolic Church of God, and likewise by the holy Fathers and the five venerable universal Councils, let him be condemned.”(DENZ. 270)
Pope St. Leo IX, Congratulamur Vehementer: “Furthermore, I declare anathema every heresy raising itself against the holy Catholic Church, and likewise him whosoever has honored or believes that any writings beyond those which the Catholic Church accepts ought to be held in authority or has venerated them. I accept entirely the four Councils and I venerate them as the four Gospels, because through four parts of the world the universal Church, upon these as on square stone, has been founded *. . . . Equally I accept and venerate the three remaining Councils. . . . Whatever the above mentioned seven holy and universal Councils believe and praise I also believe and praise, and whomever they declare anathema, I declare anathema.”(DENZ. 349)
Pope Leo X, Encyclical Exsurge Domine: “29. A way has been made for us for weakening the authority of Councils, and for freely contradicting their actions, and judging their decrees, and boldly confessing whatever seems true, whether it has been approved, or disapproved by any Council whatsoever.-Condemned (Errors of Martin Luther)”
Pope Pius IV, Iniunctum Nobis: “I acknowledge the holy Catholic and apostolic Roman Church as the mother and teacher of all churches; and to the Roman Pontiff, the successor of the blessed Peter, chief of the Apostles and vicar of Jesus Christ, I promise and swear true obedience.
Also all other things taught, defined, and declared by the sacred canons and ecumenical Councils (Profession of Faith of the Council of Trent)…”(DENZ. 999, 1000)
Pope Alexander VIII, Inter Multiplices: “So there is in the Apostolic See and in the successors of Peter, the vicars of Christ, such full power over spiritual things that the decree concerning the authority of the General Councils which are contained* in the fourth and fifth sessions of the sacred ecumenical Council of Constance are valid, and at the same time always remain unchanged, since these decrees have been approved by the Apostolic See and confirmed by the use of the Roman Pontiffs themselves…”(DENZ.1323 2)
My Comment: Many false “traditionalists” now days like to claim that Vatican II was not infallible and that we may disregard anything we judge to be unorthodox. This is erroneous because if one is going to say that Vatican II was an Ecumenical Council of the Catholic Church, one may not disagree with any information contained in it. According to the quotes above, one must obey and accept not only things defined in a council, but anything merely taught or declared. So whether one wants to say Vatican II did or did not define anything, doesn’t matter, one must obey everything because a Council is an act of the Infallible Magisterium of the Church.