magis autem pro hac sententia illud diceretur, quod alias idem poeta dicit:

πρίατο κτεάτεσσιν ἑοῖσιν.

sed uerior est Neruae et Proculi sententia: nam ut aliud est uendere, aliud emere, alius emptor, alius uenditor, sic aliud est pretium, aliud merx: quod in permutatione discerni non potest, uter emptor, uter uenditor sit.

2. Est autem emptio iuris gentium, et ideo consensu per

from one person to another consists of other goods;' but where it consists partly of other goods and partly of money (cp. L. 79 infra), the contract is deemed to be sale (Sheldon v. Cox (1824) 3 B. & C. 420): it is also proposed that the provisions relating to sales shall apply to exchange with any necessary modifications.' The proper remedy, where one of the exchanging parties has delivered goods and the other omits to send goods in return, is to bring an action for breach of the agreement, not for goods sold; a contract of barter cannot be changed into a contract to pay in money, unless the parties come to a fresh agreement to that effect, as by striking a balance in money (Harrison v. Luke (1845) 14 M. & W. 139). See further, Benjamin, Sale, p. 3, note (e).

In Scots law the two contracts are on the same footing as regards moveables, but there is an important distinction between a sale and an exchange (excambion') of lands. In sale, warrandice is a personal obligation, unless there is an express agreement for real warrandice; but in excambion there is an implied real warrandice, in virtue of which the party suffering eviction from the subject he has received in exchange has a right of recourse upon his own lands in preference even to third parties who may have acquired rights. Ersk. ii. 3. 28.

§ 2. Mancipatio, which was to some extent the forerunner of contract of sale in the early law, required for its validity a solemn ceremonial to which aliens could not competently be parties. Informal sales by bare agreement were no doubt common, but the early law did not recognise them as grounds of action unless some solemnity of word or deed was superinduced upon them by oath, stipulation, nexum, or the like, for 1 Od. i. 430.

the words used by the same poet in another place: he bought her with his wealth.' But the view of Nerva and Proculus is the truer one; for as we distinguish between buying and selling and between buyer and seller, so the wares and the price are different things; but in barter we cannot determine which is buyer and which is seller.

2. Sale is a contract iuris gentium, and is therefore completed

which the presence of the parties was an indispensable requisite. The distinctive point about contract of sale is, that it depends on simple consent, which of itself creates mutual rights and duties such as delivery and payment. This effect is here ascribed to the Jus Gentium, a phrase vaguely denoting that body of institutions and rules which was originally adopted or worked out by the praetor peregrinus to regulate the dealings of aliens inter se or with citizens, and was gradually sanctioned by the authority of the urban praetors and the jurists as binding between citizen and citizen also, till it ultimately became a main department of the Roman law, parallel to the jus civile, but applicable to all freemen alike.

The consensual and real contracts were wholly institutions of this law of nations.' As regards sale, the all-important stage in its history was the recognition of a formless agreement to sell as actionable, and the conversion of the early form of the actio empti, which was based upon stipulations and express agreements, into a bonae fidei action, a change which probably took place in the last century of the Republic. One of the chief advantages of the new system was that parties in different places could now negotiate a sale, because it required no words of style as a stipulation did, and consent might be notified by letter or verbal message.

It may be remarked in this connection that the Roman texts threw no light on the difficult questions as to the time at which a contract by correspondence is to be held as completed, or within which a retractation of a proposal or an acceptance can be effectually made. The peculiar character attaching to the modern postal and telegraph services would in any case have altered the conditions of the problem. Still the theoretical discussions of the modern civil lawyers are interesting, e.g.

agitur et inter absentes contrahi potest et per nuntium et per litteras.

Vangerow, § 603; Windscheid, § 306: the extreme views are (1) that there is no contract till the second party's acceptance of the first party's offer is brought to the knowledge of the latter; and on the other side (2) that a manifestation of will or intention to accept closes the bargain, even before it is communicated to the proposer: but there is great variety of opinion among the partisans of the second view as to how much must be done in order to bind the proposer and bar him from a revocation of his offer; some hold the writing of a letter of acceptance, some its despatch, some its arrival at the destination. fixed, to be sufficient notice to make the bargain absolute.

By our law the contract is concluded by the posting of the acceptance within the prescribed or a seasonable time, no matter what becomes of the letter afterwards. Dunlop v. Higgins (1848) 1 H. L. C. 381; Household Fire Insurance Co. (1879) 4 Ex. Div. 216; cp. Pollock, Contract, p. 32 sq. and note B; Bell, Princ. § 78.

Terminology. The terms employed in connection with sale are of some interest. The bilateral contracts, especially sale and hiring, are frequently denoted by double expressions (emptiovenditio, locatio-conductio) corresponding to the twofold aspect of the transaction. But such precision of language is unnecessary, for the one term necessarily calls up the other by association, and would also be excessively cumbrous for ordinary purposes. Hence we find that where no emphasis is to be laid on the mutual relationship of the parties, the legal writers use either expression indifferently to designate the contract as a whole, e.g. Ulpian in L. 2, just as the French and we ourselves usually speak of vente' sale,' while the Germans from the opposite point of view call it 'kauf.' It is, perhaps, an indication of a certain liking for legal pedantry in the Roman mind, that we not uncommonly meet with tautologies of this kind in lay writers also.

Ihering makes too much of the double names sometimes applied to the bilateral contracts when he presses this usage into the service of his peculiar theory that the Romans never conceived

by consent, and may be concluded by messenger or letter, without the parties being present.

of bilateral obligation in our sense at all, and that these contracts really consisted of two unilateral agreements (originally two stipulations) placed side by side, and yet mutually independent. Cp. Mommsen, Beiträge, iii. 418.

Emere, as its compounds indicate, and as Festus remarks in three places, had in early Latin the same sense as sumere (take) or accipere (take of consent, i.e. receive), but there seems to be no example of this use in the classical authors; even in Plautus it means to buy, to acquire for an equivalent in money. There is no warrant for the assumption that the original meaning survived alongside of the specialised sense.

The verb and its derivatives (emptio, emptus) are used of two stages in a sale, sometimes of the conclusion (perfectio) of the contract, sometimes of its performance and the resulting acquisition of property rights.

Merx is used by Paul in this text as a technical term for the thing sold as opposed to the price, when he is pointing out the distinction between sale and exchange. He probably felt that res was too ambiguous for this purpose. It may be noted that merx does not occur in the definitions of sale given by Gaius (iii. 149, sq.), and in the Institutes (iii. tit. 23). Elsewhere it is used without special reference to sale, in the general sense of 'merchandise,' 'wares,' and it is said not to apply to immoveables nor to slaves (D. 50. 16. 66; ib. 207).

Mercari is merely a synonym for emere, as distrahere is for vendere.

Alienare includes, of course, many other forms of divesting oneself of property besides sale. It connotes nothing more than the parting with a thing; sometimes as opposed to sale it implies transfer of ownership (D. 50. 16. 67 pr.; ib. 28).

Lastly, lex venditionis is a phrase that frequently occurs to denote the terms which the parties have agreed on when making their bargain; any special condition, reservation, or obligation was incorporated in the lex, which apparently might be either written or oral. Compare the expressions legem dare fundo, lex pignoris, lex censoria, and the like, in the Digest, passim.

2. ULPIANUS libro I ad Sabinum.

Inter patrem et filium contrahi emptio non potest, sed de rebus castrensibus potest.

1. Sine pretio nulla uenditio est: non autem pretii numeratio, sed conuentio perficit sine scriptis habitam emptionem.

L. 2 pr. So rigorously did the early law insist on the unity of the family, and its subordination to its one head, that no dependent member of it could hold property for himself; and it was a corollary of this, that there could be no civil obligation between a filiusfamilias and his paterfamilias, or any other person subject to the same potestas (D. 5. 1. 11; Gaius, iv. 78), though there might be natural obligation. In the early Empire this incapacity was removed, to a limited extent, both as regards property and obligation: a filius might have a separate estate belonging to him in full property, consisting of his acquisitions as a soldier on active service (castrense peculium), in respect of which he could contract even with his father on an equal footing: filii familias in castrensi peculio uice patrum familiarum funguntur (D. 14. 6. 2). The same doctrine was extended, under Constantine and his successors, to a son's earnings in the Civil Service and the Church (peculium quasi-castrense).

§ 1. It was a settled rule that a definite (certum) price was of the essence of sale, Inst. iii. 23. 1; and further, the price must be serious (L. 36), i.e. there must be intention to exact it; but it was sufficient for the validity of the contract that there had once been a price really incumbent upon the buyer to pay nonpayment, or release from payment at a later date, did not nullify the sale. Code iv. 38. 9: empti fides ac uenditi sine quantitate nulla est: placito autem pretio non numerato, sed solum tradita possessione istiusmodi contractus non habetur irritus, nec ideirco is qui comparavit minus recte possidet quod soluta summa quam dari conuenerat negatur. Cp. Pothier, Vente, § 18.

The requirement of certainty did not mean that the price must of necessity be stated in the contract, but only that it should be determinable in the manner therein agreed on. In particular, it may here be noted that, according to a special decision of Justinian (Code iv. 38. 15; cp. Inst. iii. 23. 1), an agreement that the price should be fixed by the valuation of a third party named