seized his kingdom and tried to seize the empire; therefore he is guilty of perjury. It is objected that we have already declared such oath to be illegal, and that he is not guilty of perjury in not keeping it, because we have said it ought not to be kept. But even if the oath was unlawful, he should not have broken it on his own authority, but should first have consulted us, after the example of the children of Israel, in the case of the oath which they swore to Gibeon; for although the oath had been won from them by fraud they did not break it of their own accord, but decided to consult the Lord. Moreover since whatever is done against the conscience leads to hell (according to the words of the apostle: "Whatsoever is not of faith is sin" [Rom. 14:23]), and since Philip excuses himself in this matter by saying that he would not have taken the kingdom if he had not known that otherwise some other persons would have seized it, it is clear that he believed he ought to have kept the oath, and that in violating it he went against his own conscience. So it seems that we ought to oppose him and resist his attempt to hold the empire, since he is legally under excommunication and is guilty of perjury. It appears also that we may properly oppose his election, for by his succession, brother will be succeeding brother, just as formerly son succeeded father when Frederick handed on the crown to his son [Henry VI] and Henry tried to do the same for his son [Frederick II]; and thus the empire tends to become hereditary, the abuse becoming law by long custom. Also it appears expedient to oppose him, for he is a persecutor, and of a race of persecutors, and if we do not oppose him now we shall be arming our enemy against ourselves.