Obligatoriness of agreements made by proxy
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Agreements made by proxy are obligatory.
From hence it followeth that when the actor maketh a covenant by authority, he bindeth thereby the author no less than if he had made it himself; and no less subjecteth him to all the consequences of the same. And therefore all that hath been said formerly (Chapter XIV) of the nature of covenants between man and man in their natural capacity is true also when they are made by their actors, representers, or procurators, that have authority from them, so far forth as is in their commission, but no further.
And therefore he that maketh a covenant with the actor, or representer, not knowing the authority he hath, doth it at his own peril. For no man is obliged by a covenant whereof he is not author, nor consequently by a covenant made against or beside the authority he gave.
When the actor doth anything against the law of nature by command of the author, if he be obliged by former covenant to obey him, not he, but the author breaketh the law of nature: for though the action be against the law of nature, yet it is not his; but, contrarily, to refuse to do it is against the law of nature that forbiddeth breach of covenant.
And he that maketh a covenant with the author, by mediation of the actor, not knowing what authority he hath, but only takes his word; in case such authority be not made manifest unto him upon demand, is no longer obliged: for the covenant made with the author is not valid without his counter-assurance. But if he that so covenanteth knew beforehand he was to expect no other assurance than the actor's word, then is the covenant valid, because the actor in this case maketh himself the author. And therefore, as when the authority is evident, the covenant obligeth the author, not the actor; so when the authority is feigned, it obligeth the actor only, there being no author but himself.
Hobbes, Lev XVI 5-8