In such questions, however, the persons we must look to are the actual parties to the contract, not those who may be entitled to sue under it: when my slave, or a son under my power, buys in his own name in my presence, the question is not what is in my mind, but what is in the mind of the contracting party.

But if you knowingly sell to my slave or mandatary a slave whom I know to be a runaway, though he does not know it, undoubtedly no action on purchase is maintainable against you.

But what if both parties were mistaken about the nature and quality of the thing; for example, if I thought I was selling and you thought you were buying gold, when it was bronze? or suppose that an heir bought from his co-heirs at a very high price a bracelet, described as being of gold but afterwards found to consist in great part of alloy. It is certain that the sale is good because there is some gold in it. For if a thing, which I took to be pure gold, contains an admixture of gold, that will support a sale: but if bronze be sold as gold, the sale is void.

competent at the instance of either (D. 21. 1. 51, 1). (b) If the mandatary is unaware but the mandant knows, the former can maintain the actio redhibitoria, and cannot be met by the plea that his principal knew all the while (D. loc. cit.); but if, as is figured here, the mandant sues the action, he can be effectually met by the plea of fraud. See as to fugitive slaves, L. 35, 3 infra.

L. 14. Savigny thinks that we are to understand from the words ambo errarent that the vendor in the examples put in LL. 9-11 supra was under no mistake himself, and from the phrase aes pro auro uencat that he was cognisant of the vendee's mistake, and was guilty of a fraud or deceit upon him. If so, the fraud would entail other consequences besides the reduction of the sale, e.g. obligation to indemnify the vendee for any prejudice he may have sustained.

15. PAULUS libro v ad Sabinum.

Et si consensum fuerit in corpus, id tamen in rerum natura ante uenditionem esse desierit, nulla emptio est.

1. Ignorantia emptori prodest, quae non in supinum hominem cadit.

Materia and qualitas are perhaps not synonyms; they may refer to distinct cases, (1) error as to the stuff or material, (2) error as to its quality or goodness.

Inauratum probably means that the thing is made of a mixture of gold and alloy, not that it is gilded or plated: the latter is expressed by cooperta auro' in L. 41, 1. harmonises the two texts in this way.

Cujas

It seems that in a stipulation a mistake as to the material properties did not make the transaction void, if parties were agreed as to the specific subject (corpus). D. 45. 1. 22; cp. Inst. iii. 19. 23; D. 13. 7. 1, 2 (pledge). The reason for this difference (according to Ihering, Geist, ii. 428) is that the formal contracts reflect the materialism of the old strictum jus from which they emanated, while sale looks to the intention more than the external fact in the spirit of the later jurisprudence to which it belongs. Even in sale we trace a development of opinion for Marcellus (9, 2 supra) argued that, when a buyer mistook a bronze vase for gold and paid for it as such, it was this vase he wanted after all, and the sale must stand quia in corpus consensum est; but Ulpian answered No; the sale is void, for his will was directed not to the external appearance of the vase, but to the essential qualities he assumed it possessed—fitness for its purpose, genuineness, and the like: the latter is the accepted doctrine of the Pandects.

L. 15 pr. If the subject sold had perished or been totally destroyed before the contract was complete, the sale was absolutely void; and the knowledge or other state of mind of the parties made no difference to the rule, which, as Savigny remarks (Syst. iii. 303), is an argument against mistake being considered the ground of nullity in these cases. It should also be noticed that a stipulation was void in such a case (D. 44. 7. 1, 9), while it was valid in spite of essential error, other than

15. PAUL.

Though the specific subject has been agreed upon, yet if it has ceased to exist absolutely before the completion of the contract, the sale is void.

1. It is only such ignorance as does not bespeak a careless man that will avail the purchaser.

error in corpore. The jurists seem to have based the rule rather on the ground of impossibility of performance owing to the nonexistence of the subject. Cp. h. t. L. 8 pr. (no sale sine re); ib. 44; D. 18. 4. 7. As to partial destruction, see infra LL. 57, 58.

The proposed rule in S. G. B. § 6-Where there is a contract for the sale of specific goods, and the goods unknown to the seller have ceased to exist at the time of the contract, the contract is void,' is based on Couturier v. Hastie (1856) 5 H. L. Ca. 673 (sale of a specific cargo previously lost), a case which proceeded on the view that, the parties having contemplated something as existing which was really non-existent, the agreement failed for want of any real contents. It was unsuccessfully argued for the defence that the expectation (spes) of a cargo, subject to whatever might have happened after it was shipped, was what the parties meant to contract about. Cp. Strickland v. Turner (1852) 7 Ex. 208, where the sale of an annuity dependent on a life that had, unknown to either, already expired at the date of the contract was held void, and the purchaser obtained return of the price.

§ 1. For the rule that ignorance of fact due to gross carelessness is not a ground of relief, see D. 22. 6. 6, nec supina ignorantia ferenda est factum ignorantis: D. 21. 1. 55, non dissolutam ignorationem emptoris excusari oportebit. The prejudicial effects that seem to be due to ignorance are really attributable to the negligence which causes it. Ignorance of law was in general no excuse; it was presumed to be culpable, for law is limited while fact is infinitely various and difficult to interpret (D. 22. 6. 2; ib. 9, 2: D. 17. 1. 29, 1). It was observed in Cooper v. Phibbs, L. R. 2 H. L. 149, that in the maxim ignorantia juris neminem excusat 'the word jus is used in the sense of denoting general law, the ordinary law of the country. But when the word jus is used in the sense of denoting a private

2. Si rem meam mihi ignoranti uendideris et iussu meo alii tradideris, non putat Pomponius dominium meum transire, quoniam non hoc mihi propositum fuit, sed quasi tuum dominium ad eum transire: et ideo etiam si donaturus mihi rem meam iussu meo alii tradas, idem dicendum erit.

16. POMPONIUS libro IX ad Sabinum.

Suae rei emptio non ualet, siue sciens siue ignorans emi: sed si ignorans emi, quod soluero repetere potero, quia nulla obligatio fuit. 1. Nec tamen emptioni obstat, si in ea re usus fructus dumtaxat ementis sit :

17.

PAULUS libro XXXIII ad edictum.

officio tamen iudicis pretium minuetur.

right, that maxim has no application. Private right of ownership is a matter of fact; it may be the result also of matter of law; but if parties contract under a mutual mistake and misapprehension as to their relative and respective rights, the result is that that agreement is liable to be set aside as having proceeded upon a common mistake.'

The English cases on recovering back money paid under a mistake of fact do not harmonise with the civil law, for negligence is not held to bar the right: the possession of the means of knowledge has no force except as evidence going to show that in fact the party was not mistaken. Kelly v. Solari (1841) 9 M. & W. 54; Balfour v. Smith (1877) 4 R. 454; Bell, Prin. § 534.

§ 2. Mistake as to the ownership of a thing (error in dominio) was in general not fatal to a contract about the thing, but it prevented transfer of the property by delivery if it was such as to be inconsistent with the intention to alienate. Cp. D. 41. 1. 35 si procurator meus uel tutor pupilli rem suam quasi meam uel pupilli alii tradiderint, non recessit ab eis dominium et nulla est alienatio, quia nemo errans rem suam amittit: which is not irreconcileable with D. 17. 1. 49; see Vangerow, i. § 311.

:

LL. 16-18.-An agreement to buy one's own property was void, whether the buyer was under a mistake as to the fact or

2. If I buy a thing from you, not knowing that it belongs to me already, and by my direction you deliver it to a third person, Pomponius holds that my right of property is not transferred, because that was not my intention, but that your supposed ownership should pass to him; and the same result follows when you intend to make me a gift of something already mine, and at my request you hand it over to some other person.

The owner of a thing cannot validly purchase it, whether he knows it is his or not: but if he bought it by mistake, he can recover what he paid for it, because no obligation ever existed.

1. But a man is not barred from purchasing a thing by having merely the usufruct of it:

17. PAUL.

but it will be the duty of the judge to make a deduction from the price in such a case.

not in the latter case, however, he could not recover the price by condictio indebiti, for he had paid what he knew he did not owe. The ground of the nullity was not the mistake, but the fact that an essential element of contract was wanting, for neque pignus, neque depositum, neque precarium, neque emptio, neque locatio rei suae consistere potest (D. 50. 17. 45 pr.; cp. C. iv. 38. 4. 10; L. 39 pr. infra; D. 19. 2. 9, 6). The principle was stated in this way, according to Ihering, in order to enable an owner, who had bought a thing in ignorance of his right of property, to make it effectual against the seller suing for the price. In the older system of pleading the plea of ownership could not be stated directly as a defence to an action on contract; it had to be put in the form of a denial of the ground of action : the sale is void, because its subject is my property. If the owner bought in the knowledge of his right, the law construed his intention so as to make it consistent with the fact; thus it substituted the idea of purchase of possession for purchase of property in such a case (L. 34, 4). A conditional purchase of a thing, in which one had a right of property defeasible in a certain