How good faith may be tacitly interposed

[C]ertain things are agreed to by silence; and this is found to be the case in public agreements, in private agreements, and in mixed agreements. The reason is that consent, no matter how indicated and accepted, has the power of transferring a right. But there are also other signs of consent besides spoken and written words, as we have already more than once indicated. And certain signs by nature form a part of the act.

The case of a person who desires to be received under the protection of a people or a king

An example may be found in the case of the person who comes either from the enemy or from a foreign country and entrusts himself to the good faith of another people or king. For there ought to be no doubt that such a person tacitly binds himself to do nothing against that government under which he seeks protection.

The case of one who asks or grants a parley

Likewise the person who asks or grants a parley tacitly promises that it will be without hurt to those who take part in it.

Whether a person who asks or grants a parley is hindered from promoting his own interests

But that implied consent must not be extended beyond what I have said. For, provided that the parties to the conference suffer no harm, it is not treacherous, but reckoned among honourable artifices, to divert the enemy from warlike plans by the pretext of a parley, and in the meantime to promote one’s own advantage.