Not to oppose erroneous doctrine is to approve of it, and not to defend at all true doctrine is to suppress it.

The Pope should not flatter himself about his power nor should he rashly glory in his honor and high estate, because the less he is judged by man, the more he is judged by God. Still the less can the Roman Pontiff glory because he can be judged by men, or rather, can be shown to be already judged, if for example he should wither away into heresy; because he who does not believe is already judged, In such a case it should be said of him: 'If salt should lose its savor, it is good for nothing but to be cast out and trampled under foot by men.'

Not to oppose erroneous doctrine is to approve of it, and not to defend at all true doctrine is to suppress it.

We believe that the Greeks have been punished through [the Crusades] by the just judgement of God: these Greeks who have striven to rend the Seamless Robe of Jesus Christ ... Those who would not join Noah in his ark perished justly in the deluge; and these have justly suffered famine and hunger who would not receive as their shepherd the blessed Peter, Prince of the Apostles.

Every cleric must obey the Pope, even if he commands what is evil; for no one may judge the Pope.

If it shall be necessary, through sentences of excommunication against their persons and of interdict against their lands, all backsliding being put an end to, they compel them to fulfil their vows.

So much must I live for others, that almost I am a stranger to myself.