But I do not admit that there is an opportunity for such a choice (whatever Baldus and Romanus may do) against one of two federates to the advantage of the other. 'If he cannot aid one without injury to the other, it is better not to help the one than to do harm to the other', as the words of Ambrose run; and that is the sense of the law and the rule which rates the avoidance of harm above the consideration of gain. What if, in order to benefit one federate, it is necessary to wrong the other doubly ? If two brothers who are lords of a feudal subject wage war upon each other, the vassal is bound to aid neither of them, since they mutually oppose each other, says Baldus. And allies mutually interfere with one another, as happens in other cases, which Romanus notes.