The very office of construction is to work out, from what is expressly said and done, what would have been said with regard to events not definitely before the minds of the parties, if those events had been considered. The price paid in mercantile contracts generally excludes the construction that exceptional risks were intended to be assumed. The foregoing analysis is believed to show that the result which has been reached by the courts on grounds of practical good sense, falls in with the true theory of contract under the common law. The discussion of the nature of a promise has led me to analyze contract and the consequences of contract somewhat in advance of their place. I must say a word more concerning the facts which constitute a promise. It is laid down, with theoretical truth, that, besides the assurance or offer on the one side, there must be an acceptance on the other. But I find it hard to think of a case where a simple contract fails to be made, which could not be accounted for on other grounds, generally by the want of relation between assurance or offer and consideration as reciprocal inducements each of the other. Acceptance of an offer usually follows by mere implication from the furnishing of the consideration; and inasmuch as by our law an accepted offer, or promise, until the consideration is furnished, stands on no different footing from an offer not yet accepted, each being subject to revocation until that time, and each continuing [304] until then unless it has expired or has been revoked, the question of acceptance is rarely of practical importance. Assuming that the general nature of consideration and promise is understood, some questions peculiar to bilateral contracts remain to be considered. These concern the sufficiency of the consideration and the moment when the contract is made. A promise may be a consideration for a promise, although not every promise for every other. It may be doubted whether a promise to make a gift of one hundred dollars would be supported by a promise to accept it. But in a case of mutual promises respectively to transfer and to accept unpaid shares in a railway company, it has been held that a binding contract was made. Here one party agrees to part with something which may prove valuable, and the other to assume a liability which may prove onerous. /1/