Unilateral mistake.

If one manifest a certain intention, he is estopped from proving that his real intention was different.

Thompson v. Leach, 2 Vent. 198, 202, 208; 2 Prest. Abst. 226 - 228; Siggers v. Evans, 5 E. & B. 367, 380 sq; Expte. Cote, L. R. 9 Ch. 27. 32; Standing v. Bow-ring, 31 Ch. D. 282 ; Mallott v. Wilton, 1903, 2 Ch. 494.

(f) See Thoroughgood's case, 2

Rep. 9 ; below, pp. 671, 672.

(g) BenjaminonSale,45, 2nded.

(h) Freeman v. Cooke, 2 Ex. 654, 663; Cornish v. Abington, 4 H. & N. 549, 555, 556; Smith v. Hughes, L. R. 6 Q. B. 597, 607, 609; Smith v. Chadwich, 9 App. Cas. 187, 190.

(i) The writer is aware that it is contended by eminent jurists that the law has no concern at all with the real intentions of the parties to a contract, but can only regard the intention which they have outwardly manifested; O. W. Holmes, The Common Law, 309; Holland, Jurisprudence, 246 - 252, 9th ed. It is nevertheless submitted that the common law of England is as stated in the text, and recognises, as a rule of pure law (so pure that it rarely emerges from the region of abstract theory into concrete shape), that the true consent of the parties is necessary to make a valid contract. This precept of perfection is almost always obscured by the operation of the qualifying law of estoppel by outward manifestation of consent. But it is contended that the principle, that true consent is necessary to make a contract, is exhibited in the case where the terms of a written contract contain a latent ambiguity with regard to the subject matter thereof. Thus in the well-known case of Raffles v. Wichelhaus, 2 H. & C. 906, where the plaintiff sued for breach of a contract for the sale of goods "to arrive ex Peerless," it was pleaded that the defendant meant a ship so called which sailed from Bombay in October, but the plaintiff had not offered any goods arriving by this ship in fulfilment of the contract, and had only offered goods arriving by another ship of the same name; and this was held upon the plaintiff's demurrer to be a good plea. This decision shows that where there is no true consent, there is no contract. But if the plea had been set up fraudulently, it would have been competent to the plaintiff to join issue thereon and to give evidence that the defendant really meant the same ship as the plaintiff; see cases cited, below, pp. 677, n. (p), 699, n. (s); Smith v. Thompson, 8 C. B. 44, 59, 60; Bruff v. Conybeare, 13 0. B. N. S. 263, 274, 275. It thus appears that ultimately the law does regard the parties' real intention. If this were not so, and the law were never concerned with anything but what the parties have said, every contract expressed in terms similar to that in Raffles v. Wichelhaus would be void for uncertainty so soon as it appeared that the description could be applied to more than one object, and no further evidence would be admissible. But that is not the law. If I have two estates called Blackacre, one in Hampshire and the other in Northumberland, and I contract with J. S., who knows nothing of my estate in Northumberland, but whom I have shown over my estate in Hampshire as an intending purchaser, to sell to him "my estate called Blackacre," this contract is not rendered void for uncertainty on my proving that I have another Blackacre in Northumberland, but J. S. is at liberty to give oral evidence that I took him over Blackacre in Hampshire and offered to sell that property to him, and so to prove that that property is what was really referred to or meant by both parties in the written memorandum under the description of "my estate called Blackacre." It must be admitted, however, that there is authority for the theory that, in such cases, the question is not what did the parties intend, but is, what is the signification of the words they have used; Parke, J., Richardson v. Watson, 4 B. & Ad. 787, 800 ; and see L. Q. R. xx. 245. This view is upheld by Mr. Justice O. W. Holmes, The Common Law, p. 309, where he maintains that the true ground of the decision in Raffles v. Wichelhaus was, not that each party meant, but that each said a different thing ; see also Harvard Law Review, xii. 417. But considering that each party, in so far as he said anything at all, used the very same words, it could only be established that they said a different thing by showing that the word used signified to the mind of the plaintiff one ship and to the mind of the defendant another, or held out to the defendant's mind one meaning and to the plaintiff's another. The difference between proving what was in the parties' minds as to the signification of the word used, and proving what was their intention, seems to be very fine. And upon either view of the matter, the plaintiff was at liberty to prove, if he could, that the parties' minds were at one as regards the meaning of the word Peerless. It seems therefore that the law does sometimes take account of what passes in men's minds, and does in this instance require that the parties' minds shall be at one. And it is submitted that, if the outward manifestation were alone to be regarded, there could be but one conclusion in all such cases, namely, that the parties have said what is ambiguous and therefore void for uncertainty. Again, where A. is induced by the fraud of B. to sign a contract for the sale of his land to C. in the belief that he is signing an agreement for a lease, A. would surely be bound, if the outward manifestation of his intention could alone be considered. But he is at liberty to prove that his intention did not accompany his apparent act, and is not bound, unless he be estopped by his negligence; see below, pp. 671 - 673. It may perhaps be more readily maintained in this case that A. is not bound because he and C. have not really said the same thing, have not in truth joined in the expression of consent; see O. W. Holmes, The Common Law, 308, 309. But it may be replied that to all outward appearance A. and C. have said the same thing, for A. has himself affixed his own signature to the document: but A. did not mean to do so; and in the particular circumstances he is not precluded from giving evidence as to the state of his own mini at the time when he signed the writing. It is further submitted that, upon a general view of the law of England, taking in the rules of equity as well as of common law, we can hardly fail to recognise the principle, that there ought to be true consent to make a contract. It was on this principle that Courts of Equity would refuse to enforce specific performance of a contract wanting in the element of true consent, though valid, on the ground of manifested consent, at law. Not until Not until the year 1880 was it decided that the law of estoppel through manifestation of consent may prevail over this principle in the matter of enforcing specific performance of the contract as it may in determining the validity of the agreement at law; Tamplin v. James, 15 Ch. D. 215. And though the rule requiring true consent is now so qualified, it is nevertheless still open to Courts of Equity to give effect to it by refusing specific performance where there is a want of true consent and it would work great hardship on the mistaken party to apply the law of estoppel. See below, pp. 691 - 693 and n. (p), and above, p. 636.