It follows from the principle that expressed mutual assent rather than actual mental assent is the essential element in the formation of contracts,5 that a mistaken idea of one or both parties in regard to the meaning of an offer or acceptance will not prevent the formation of a contract. Such a mistake may, under certain circumstances be ground for relief from the enforcement of the contract.6 But this relief is in its origin equitable, and is in its nature a defence to the enforcement of the contract of which advantage may or may not be taken, rather than a defect in the formation of the contract.7 It follows that the test of the true construction of an offer or acceptance is not what the party making it thought it meant or intended it to mean, but what a reasonable person in the position of the parties would have thought it meant.8 late acceptance. . . . These considera-tions have such force that they have led to some legislation imposing on every one who has made an offer by correspondence the duty to inform his correspondent that the acceptance has arrived too late. German Commercial Code, Art. 319; Swiss Federal Code of Obligations, Art. 5;" Valery, Contrats par Comapondance, Sec.203.
3 Phillips v. Moor, 71 Me. 78.
4 The situation is of the sort discussed at the end of Sec. 9Ia.
7 Woburn Nat. Bank v. Woods, 77 N. H. 172, 89 Atl. 491.
8 Balnea v. Woodfall, 6 C. B. (N. S.) 657; Smith v. Hughes, L. R. 6 Q. B. 597; Ireland v. Livingston, L. R. 5
The sound view has been well expressed by L. Hand, J.: 9 "A contract has, strictly speaking, nothing to do with the personal, or individual, intent of the parties. A contract is an obligation attached by the mere force of law to certain acts of the parties, usually words, which ordinarily accompany and represent a known intent. If, however, it were proved by twenty bishops that either party, when he used the words, intended something else than the usual meaning which the law imposes upon them, he would still be held, unless there were some mutual mistake, or something else of the sort. Of course, if it appear by other words or acts of the parties, that they attribute a peculiar meaning to such words as they use in the contract, that meaning will prevail, but only by virtue of the other words, and not because of their unexpressed intent." 10 Therefore, if either party instead of communicating with the other party directly makes use of an intermediary who makes a mistake in the words transmitted, they nevertheless are binding on the party employing the intermediary.
H. L. 395; Preston v. Luck, 27 Ch. D. 497; Van Praagh v. Everidge, [19021 2 Ch. 266; Falck v. Williams,  A. C. 176; Scully v. United States, 197 Fed. 327; Bijur Motor Lighting Co. v. Eclipse Much. Co., 243 Fed. 600, 156 C. C. A. 208; Thompson v. Ray, 46 Ala. 224; Silva v. Silva, 32 Cal. App. 115,162 Pac. 142; Newsome v. Brazell, 118 Ga. 547, 45 S. E. 397; Wood v. Duval, 100 Ia. 724, 69 N. W. 1061; Lull v. Anamosa Nat. Bank, 110 Ia. 537, 81 N. W. 784; Wood v. Allen, 111 Ia. 97, 82 N. W. 451; Miller v. Lord, 11 Pick. 11; Stoddard v. Ham, 129 Mass. 383, 37 Am. Rep. 369; Mansfield v. Hodgdon, 147 Mass. 304, 17 N. E. 544; Tallant v. Stedman, 176 Mass. 460, 466, 57 N. E. 683; Home F. Ins. Co. v. Bredehoft, 49 Neb. 152, 68 N. W. 400; Woburo Nat. Bank v. Woods, 77 N. H. 172, 89 Atl. 491; American Lithographic Co. v. Commercial Casualty Co., 81 N. J. L. 271, 80 Atl. 25; Carnegie Steel Co. v. Connelly, 89 N. J. L. 1, 97 Atl. 774; Phillip v. Gallant, 62 N. Y. 256; Leonard v. Howard, 67 Oreg. 203, 135 Pac. 549; Neufville v. Stuart, 1 Hill Eq. (S. C.) 159; J. A. Coates & Sons v. Buck, 93 Wis. 128, 67 N. W. 23. But see Green v. Batsman, 2 Woodb. A M. 359; Lamar Elevator Co. v. Crad-dock, 5 Col. App. 203, 37 Pac. 960; Hartford Ac. R. R. Co. v. Jackson, 24 Conn. 514, 63 Am. Dec. 177; Rowland v. New York Ac. R. R. Co., 61 Conn. 103, 23 Atl. 755,29 Am. St. Rep. 175; Brant v. Gallup, 5 111. App. 262; Clay p. Rickets, 66 Ia. 362, 23 N. W. 765; Hogue v. Mackey, 44 Kan. 277,24 Pac. 477; Fraser v. Small, 59 Hun, 619, 13 N. Y. Supp. 468; Tucker v. Preston, 60 Vt. 473, 11 Atl. 726.
9 Hotchkiss v. Natl. City Bank, 200 Fed. 287, 293 (aff'd 231 U. S. 50, 58 L.Ed. 115, 34 S. Ct. 20). See also the elaborate opinion of Rogers, J. in Star-Chronicle Pub. Co. v. New York Evening Post, 256 Fed. 435 (C. C. A.)
10See further, infra, Sec.Sec. 606, 607, 610.
Thus, "when two parties who speak different languages and cannot understand each other, voluntarily agree upon a third person to translate for them, they make the interpreter then-agent, so that each has a right to rely on the communication made to him by the other party through his representative." 11 So if one party using a telephone asks the operator to repeat the message to a third person, the offeror is bound by the words of the operator though they do not correctly follow instructions.12 So where a telegraphic offer is sent and the telegraph company transmits the message inaccurately, the offeror is treated as having made the offer in the form in which it was received by the offeree.13 If, however, the receiver of the telegram ought to have known that there must have been a mistake in the wording of the telegram, from his knowledge of the market, or for other reasons, he cannot by accepting, bind the offeror.14 And
11 Bonelli v. Burton, 61 Ore. 429,123 Pac 37, citing Sullivan v. Kuykendall, 83 Ky. 483, 489, 56 Am. Rep. 901, and Miller v. Lathrop, 50 Minn. 91, 93, 52 N. W. 274, and adding further: "An interpreter selected by adverse parties, who apeak different languages and cannot understand each other, being the agent of both, his representations, made in their presence and bearing, in communicating to one what purport to be the expressions of the other, related in the regular course and prior to the termination of the business, are chargeable to each; and the other is entitled to rely on such representations."