Offer and acceptance

It is an undeniable principle of the law of contracts, that an offer of a bargain by one person to another, imposes no obligation upon the former, until it is accepted by the latter, according to the terms in which the offer was made. Any qualification of, or departure from, those terms, invalidates the offer, unless the same be agreed to by the person who made it. Until the terms of the agreement have received the assent of both parties, the negotiation is open, and imposes no obligation upon either.