130. Mistake is where the parties did not mean the same thing, or where one or both, while meaning the same thing, formed untrue conclusions as to the subject-matter of the agreement.

131. Mistake avoids the contract in the following cases:

(a) Where the mistake is as to the nature of a written contract.

the execution of which is induced or procured by misrepresentation;

(b) Where the mistake is as to the identity of the person with whom the contract is made;

(c) Where the subject-matter of the contract, unknown to the parties, does not exist;

(d) Where two things have the same name, and the parties, owing to the identity of names, do not mean the same subject-matter.

It must be borne in mind that we are here dealing with mistake of intention, and not mistake of expression. The parties may be genuinely agreed on the terms of their contract, but the terms may, by mistake, be so expressed as not to convey their meaning. In these cases they may be permitted to explain the contract, or the court may correct the mistake. This is mistake of expression, and pertains to the interpretation of contracts, with which we shall deal in a subsequent chapter.2

The almost universal rule is that a man is bound by an agreement to which he has expressed his assent in unequivocal terms, uninfluenced by falsehood, violence, or oppression. If he has exhibited all the outward signs of agreement, the law will hold that he has agreed. As a rule, a person cannot avoid his contract simply by showing that he has made a mistake.8 There are, however, exceptions to this general rule in the case of mutual mistake of the parties, and of mistake of one party induced by, or known to, the other. The latter is a species of fraud, and is accordingly reserved for treatment under that topic.4

1 Anson, Cont. (8th Ed.) 127. 2 See post, ch. X.

3 C. H. Young Co. v. Springer, 118 Minn. 382, 129 N. W. 773, holding mistake without effect where it was the mistake of only one party and was not Induced by, or actually known to, the other. To the same effect, see Tatum v. Coast Lumber Co., 16 lrlaho, 471, 101 Pae. 957, 23 L. R. A. (N. S.) HOD; Steinmeyer v. Schroeppel, 226 I11. 9, 80 N. E. 5G4, 10 L. R. A. (N. S.) 114, 117

"Mutual mistake," as defined in a Minnesota case,5 "consists in a clear showing of a misunderstanding, reciprocal and common to both parties, in respect to the terms and subject-matter of the contract, or some substantive part thereof." It should not be understood that mutual mistake is always sufficient to render a contract void. Where the mistake is in regard to an immaterial matter, or a mere matter of inducement, it is without effect upon the validity of the contract.6 But where the mistake goes to the essence of the contract, it renders the contract void for the want of a meeting of the minds of the parties, or because the apparent agreement is upon the assumption of that which is not true. The circumstances under which mistake renders the contract void will now be enumerated and explained.