Dei Filius, On Faith, Canon 2

2. If any one shall say that divine faith is not distinguished from natural knowledge of God and of moral truths, and therefore that it is not requisite for divine faith that revealed truth be believed because of the authority of God, who reveals it: let him be anathema.

Translation: Henry Edward Manning, Petri Privilegium (1871), reproduced in Philip Schaff, Creeds of Christendom II, via CCEL.