The principles governing revocation are wholly different.  One to whom an offer is made has a right to assume that it remains open according to its terms until he has actual [307] notice to the contrary.  The effect of the communication must be destroyed by a counter communication.  But the making of a contract does not depend on the state of the parties’ minds, it depends on their overt acts.  When the sign of the counter promise is a tangible object, the contract is completed when the dominion over that object changes.

[308] LECTURE IX.

CONTRACT.- III.  VOID AND VOIDABLE.

THE elements of fact necessary to call a contract into existence, and the legal consequences of a contract when formed, have been discussed.  It remains to consider successively the cases in which a contract is said to be void, and those in which it is said to be voidable,—­in which, that is, a contract fails to be made when it seems to have been, or, having been made, can be rescinded by one side or the other, and treated as if it had never been.  I take up the former class of cases first.

When a contract fails to be made, although the usual forms have been gone through with, the ground of failure is commonly said to be mistake, misrepresentation, or fraud.  But I shall try to show that these are merely dramatic circumstances, and that the true ground is the absence of one or more of the primary elements, which have been shown, or are seen at once, to be necessary to the existence of a contract.

If a man goes through the form of making a contract with A through B as A’s agent, and B is not in fact the agent of A, there is no contract, because there is only one party.  The promise offered to A has not been accepted by him, and no consideration has moved from him.  In such a case, although there is generally mistake on one side and fraud on the other, it is very clear that no special [309] doctrine need be resorted to, because the primary elements of a contract explained in the last Lecture are not yet present.

Take next a different case.  The defendant agreed to buy, and the plaintiff agreed to sell, a cargo of cotton, “to arrive ex Peerless from Bombay.”  There were two such vessels sailing from Bombay, one in October, the other in December.  The plaintiff meant the latter, the defendant the former.  It was held that the defendant was not bound to accept the cotton. 1 It is commonly said that such a contract is void, because of mutual mistake as to the subject-matter, and because therefore the parties did not consent to the same thing.  But this way of putting it seems to me misleading.  The law has nothing to do with the actual state of the parties’ minds.  In contract, as elsewhere, it must go by externals, and judge parties by their conduct.  If there had been but one “Peerless,” and the defendant had said “Peerless” by mistake, meaning “Peri,” he would have been bound.  The true ground of the decision was not that each party meant a different thing from the other, as is implied by the explanation which has been mentioned, but that each said a different thing.  The plaintiff offered one thing, the defendant expressed his assent to another.