The Civil law, starting from the subjective standpoint that the existence of a contractual obligation or a transfer depends upon the will of the actor instead of on the natural reliance of one party to the transaction on words or acts of the other,27 seeks to find what mistakes are so essential that the actor cannot be said to have accomplished a legal act. To this end a classification is made of misunderstanding where though there is an expression of mutual assent, there is no real assent, and essential error where though the parties mean the same thing by their expressions, and express assent, the actor does so under the assumption of the existence of an essential circumstance which in fact does not exist.

Essential error is divided into error (1), as to the nature of the transaction, (2), as to the person contracted with, and (3), as to the object to which the contract relates,28 ness. When the plaintiff took possession, several of the articles which he supposed he had purchased had been taken or were withheld, and the defendant claimed that they were not included. This, however, did not prove that no contract had been made. If they had been taken by the defendant and belonged to the plaintiff, the plaintiff's legal rights were secure. But these rights grew out of the existence, and not out of the non-existence, of the contract itself."

27 Even in the Civil law the em-phasis seems increasingly laid on outward manifestation and reliance thereon. In the German Civil Code (Sec. 119, 120), it is indeed stated that a declaration of will may be avoided if made under a material mistake, or if incorrectly communicated; but it is also enacted (Sec. 122) that under these circumstances the declarant must compensate one who relies on the declaration. In the Swiss Code of Obligations, the editor (Rossel) says (p. 4), "Our Code has adopted the theory of declaration of will - the Erklarungstheorie, the intent of the parties based on agreement of intention which they have reciprocally manifested, and not on their intention itself."

26 "Cases of essential error. These cases agree in this, that the actor intends an expression of his will and a juristic result; but he does not express the juristic result which he intends,- rather he expresses another which he does not intend, without being aware, however, that he does not intend it. In cases of essential error, the transaction is invalid. . . . The particular cases of essential error are as follows:

" 1. Error as to the nature of the transaction (error in negotio) - the actor intends to conclude a different transaction from that which he expresses; for example, he signs a bill of sale in the supposition that it is a lease.

"2. Error with respect to the person (error in persona) - the actor intends a different party than the one for whom he has expressed himself. But it is to be observed that this error is without interest to the actor in those cases in which the person is indifferent (e. g.,

This classification serves sufficiently to classify by their dramatic facts cases as they ordinarily arise; but in the English and American law, the classification has no further value. Neither the rights nor the remedies of the parties depend upon it. Misunderstanding may render an agreement void, but it may not be even voidable.29 Error in regard to the person may render a transaction void;30 it may be rendered voidable,31 or it may be perfectly enforceable, the mistake having no effect.32

A mistake as to the object to which the agreement relates may sometimes render the transaction void but sometimes only voidable.33 A mistake as to the nature of the transaction may render it void,34 or voidable; 35 or may have no effect at all.36 Moreover, there are cases of mistake which do not fall within any of these categories which may, nevertheless, render a transaction voidable. No more specific rule can be given or is desirable than that already stated, - If the mistake vitally affects the basis upon which the parties contracted relief should sales for cash), and hence does not influence the validity of the transaction.

"3. Error with respect to the object (error in corpore) - the actor intends a different object from the one he named in expressing his will. In contracts of sale, error as to qualities of the object which, according to mercantile understanding, determine the nature of the object (error in substantia) stand on the same basis as error with respect to the object.

"4. The so-called misunderstanding is on the same basis as essential error. That is to say, in contracts the error is essential if by reason thereof a mutual assent results in appearance only; each party errs with respect to the will of the other and expresses an intention which does not correspond thereto. The error may have to do with the nature of the legal relation (one pays a sum as loan, the other receives it as gift, so that there is neither a loan nor a gift), or the person of the other party (one obtains a loan from A, but believes he has obtained it from B, so that there is no loan, but instead an 'unjust enrichment'), or the object (one intends to buy the Cornelian estate, the other to sell the Sempronian, so that no legal transaction results).

"Other kinds of mistake are without influence upon the validity of a legal transaction. . . . Also an error in the motive by reason of which the actor entered into the transaction, in general, is without influence upon its validity. But there are important exceptions." Baron, Pandekten, Sec. 50, II, translated by Pound, Readings in Roman Law (2d ed.), 39.

29 See Sec.Sec.94, 95.

30 See supra, Sec. 80.

31 See supra, Sec. 1517.

32 Ibid

33 See infra, Sec.Sec. 1559-1503.

34 See supra,Sec. 1488.

35 As where a writing is negligently signed but the signature was induced by fraud. See supra, Sec. 1516.

36 As where a writing is negligently signed but there was no fraud. See supra, Sec. 35.

be granted. The inadequacy of the classification just criticised seems to have been observed by the draftsmen of the German Civil Code, which contains a general provision not greatly differing from that here advocated.87 It having been noted that the classification is merely for convenience of treatment, the situations which commonly arise may be considered.