But now suppose that there is no element of uncertainty except in the minds of the parties. Take, for instance, a wager on a past horse-race. It has been thought that this would amount to an absolute promise on one side, and no promise at all on the other. /2/ But this does not seem to me sound. Contracts are dealings between men, by which they make arrangements for the future. In making such arrangements the important thing is, not what is objectively true, but what the parties know. Any present fact which is unknown to the parties is just as uncertain for the purposes of making an arrangement at this moment, as any future fact. It is therefore a detriment to undertake to be ready to pay if the event turns out not [305] to have been as expected. This seems to be the true explanation why forbearance to sue upon a claim believed the plaintiff to be good is a sufficient consideration, although the claim was bad in fact, and known by the defendant to be bad. /1/ Were this view unsound, it is hard to see how wagers on any future event, except a miracle, could be sustained. For if the happening or not happening of the event is subject to the law of causation, the only uncertainty about it is in our foresight, not in its happening. The question when a contract is made arises for the most part with regard to bilateral contracts by letter, the doubt being whether the contract is complete at the moment when the return promise is put into the post, or at the moment when it is received. If convenience preponderates in favor of either view, that is a sufficient reason for its adoption. So far as merely logical grounds go, the most ingenious argument in favor of the later moment is Professor Langdell's. According to him the conclusion follows from the fact that the consideration which makes the offer binding is itself a promise. Every promise, he says, is an offer before it is a promise, and the essence of an offer is that it should be communicated. /2/ But this reasoning seems unsound. When, as in the case supposed, the consideration for the return promise has been put into the power of the offeree and the return promise has been accepted in advance, there is not an instant, either in time or logic, when the return promise is an offer. It is a promise and a term of a binding contract as soon as it is anything. An offer is a revocable and unaccepted communication of willingness to promise. [306] When an offer of a certain bilateral contract has been made, the same contract cannot be offered by the other side. The so-called offer would neither be revocable nor unaccepted. It would complete the contract as soon as made.