It is generally said that mistake as to a collateral matter has no effect upon a contract. The boundaries of such a rule are not very exactly fixed, but it means that where the persons and things to which the contract relates are the very persons and things the parties had in mind, and the transaction is the kind of transaction they had in mind, mistakes as to other facts { are unimportant. There is considerable opportunity for casuistry in a discussion whether a mistake relates to the very object of the contract or only to its inducement or to some quality thereof; 33 and if whatever facts are assumed by the parties as the fundamental basis of their bargain are said to go to the identity or existence of the subject-matter of the contract, and all other facts are said to be collateral, mistake as to a collateral fact is merely another name for immaterial mistake. But it is not satisfactory terminology to use collateral in this sense, since a mistake may not so far affect the identity of the subject-matter (e. g. of a sale) as to prevent the property from passing, and yet may make the transaction voidable. Nomenclature should distinguish between these two kinds of mistake. Undoubtedly it is true that in contracts to buy or sell with no warranty goods specified or particularly described, the fact that the goods are better or worse than supposed or possess different qualities not affecting identity will ordinarily be immaterial/4 and the same principle is applicable to other contracts no mistake as to what the money is paid for, or the facts giving rise to the supposed obligation to pay it.36

Graham (Va.), 98 S. . 659. See also Nordyke, etc., Co. v. Kehlor, 155 Mo. 643, 56 S. W. 287, 78 Am. St. Rep. 600.

33 As for instance in Cotter v. Luckie, [1918] N. Zeal. L. R. 811, where a "polled Angus bull" was sold by auction, delivered to the buyer, and kept by him for four days; when, the bull proving impotent, the buyer sought to rescind the transaction. The conditions of the auction provided that no error or misdescription should annul a sale; but the court held that the animal was only " nominally" a bull and that no title had ever passed.

34 Kennedy v. Panama etc. Mail Co., L. R. 2 Q. B. 580; Otis v. Cullum, 92 U. S. 447, 23 L. Ed. 496; Dortic p. Dugas, 55 Ga. 484; McCobb v. Richardson, 24 Me. 82, 41 Am. Dec. 374; Stewart v. Bank, 104 Me. 578, 72 Atl. 741; Wheat v. Cross, 31 Md. 99, 1 Am. Rep. 28; Bridgewater Iron Co. v. Enterprise Ins. Co., 134 Mass. 433; Hecht v. Batcheller, 147 Mass. 335, 17 N. E. 651, 9 Am. St. 708; Cavanagh v. Tyson, 227 Mass. 437, 116 N. E. 818; Costello v. Sykes, (Minn. 1919), 172 N. W. 907; Sample v. Bridgforth, 72 Miss. 293,16 So. 876; Brown v. Pagan, 71 Mo. 563; Moore v. Scott, 47 Neb. 346, 66 N. W. 441; Dambmann v. Schulting, 75 N. Y. 55; Sankey's Exr's p. First Nat. Bank, 78 Pa. 48; Pearce v. Suggs, 85 Tenn. 724, 4 S. W. 526; Wood v. Boynton, 64 Wis. 265, 25 N. W. 42, 54 Am. Rep. 610.

In Smith v. Becker, [1916] 2 Ch. 86, 100, the court seems to have assumed that unless the mistake in question involved impossibility of performance a contract was enforceable. Phillimore, L. J., said: "Hie parties con traoted on August 1, odd as it may be, without knowledge of the embargo which had taken place on July 31. If, instead of the embargo, there had been a conflagration at Hamburg, and all the crop of sugar had been at Hamburg, and all of it had been destroyed, then I think the contract of August 1 would have been no contract, and no proceedings could have been taken for arbitration under it. But I do not think that it is made out by the plaintiffs, and I do not think it is at all likely that they could make out, that the embargo has that effect. As has been pointed out by other members of the Court, there are two ways in which the purchaser can take delivery here. He can take delivery on ship or he can take delivery into a named than those of purchase and sale, where the nature or quality of some object is involved.35 For the same reason no right to recover money paid will lie because of a mistake which merely affects the desirability of making the payment, when there is warehouse or lagerhaus. Dealing with the embargo only as made on July 31 - and that is what we have to deal with) regardless altogether of the war between Germany and Russia, which began probably on August 2, and regardless of the war between Great Britain and Germany, which began at 11 o'clock on the evening of August 4, all of which are events which happened after the contract, and which are provided for by the war clause - one sees no reason why on July 31 or August 1, the purchaser should not have named a warehouse into which the sugar, if not already there, could have been delivered without any interference by the German Government and without any violation of such embargo as we have had suggested. Perhaps it is always unwise to use words which have a technical meaning in a not strictly technical sense, and I prefer to substitute for the word 'embargo' the words 'prohibition of export,' and I see no reason why prohibition of export should have prevented a transfer from one warehouse to another, or a notional transfer of property in the warehouse from seller to buyer. Therefore it does not seem to me that the plaintiffs have made out that the contract was void or even voidable as entered into under a common mistake of fact. Therefore I think that their application for an injunction fails."

35 In Cavanagh v. Tyson, etc., Co., 227 Mass. 437, 116 N. E. 818, a contractor sought to be relieved of a contract because of the unexpectedly difficult soil in which the contract must be performed. The court said (p. 820): "The question presented is whether the erroneous belief of the plaintiff and defendant is a mutual mistake of fact of sufficient importance to make the contracts void. Such result can follow only when the mistake relates to a fact which is of the very essence of the contract, the material element in the minds of both parties, and material in the sense that it is one of the things contracted about. Long v. Athol, 196 Mass. 497, 82 N. E. 665, 17 L. R. A. (N. S.) 96; Winston v. Pittsfield, 221 Mass. 356, 108 N. E. 1038; Miles v. Stevens, 3 Pa. 21, 45 Am. Dec. 621, note; Steinmeyer v. Schroeppel, 226 I11. 9, 80 N. E. 564,10 L. R. A. (N. S.) 114, 117 Am. St. Rep. 233, note.

" In the case at bar the character of the fill through which the piles were to be driven was of importance only in the determination of the price to be demanded and paid for the performance of the work. Had the burden of performance proved less than anticipated it will scarcely be claimed that the defendant could in an appropriate action have had relief from the contract through rescission or to recover any excess in payment over reasonable compensation. Yet, such would be the defendant's right if the contract were void ab initio. Sherwood v. Walker, 66 Mich. 568, 33 N. W. 919, 11 Am. St. Rep. 531. In the case at bar the mistake of fact is collateral to the essential thing contracted about, and therefore does not invalidate the contract. Hecht v. Batcheller, 147 Mass. 335, 17 N. E. 651, 9 Am. St. Rep. 708. See Long v. Athol, supra; Rowe v. Peabody, 207 Mass. 226, 93 N. E. 604; Winston v. Pittsfield, supra; Young v. Holyoke, 225 Mass. 140,114 N. E. 62."