First Part. On Contracts in General

744.^† - Definition. A contract is an agreement by which one or several bind themselves toward one or several others to something to be given, done, or omitted.

Division. A contract is chiefly distinguished as: 1. unilateral, or bilateral. The former occurs when one or several bind themselves toward one or several not bound, as in the contract of gratuitous promise. The latter is had when one or several bind themselves toward one or several likewise bound, as in exchanges. A bilateral contract is also called synallagmatic, from the Greek words syn, with, and allasso, I exchange.

2. Gratuitous, or of beneficence, or onerous. A contract is called gratuitous if one of the contracting parties gives something to another, exacting nothing from him from obligation. But it is called onerous if each of the contracting parties obliges himself to furnish something to the other, as in a contract of sale. This division falls back into the preceding one. For a gratuitous contract is unilateral, and an onerous contract is bilateral.

But an onerous contract is again subdivided into commutative and aleatory. It is commutative if one contracting party gives a thing in one species, and the other gives an equivalent thing or one of a diverse species. It is aleatory if one gives a thing, but the other contracting party gives not a thing, but the probable hope of obtaining some thing; since this hope can fail, it effects that a contract of this kind bears before itself the likeness of chance.

3. Solemn or simple, according as it requires special formalities of law, or is subject only to common dispositions.

4. Nominated or innominate, according as it has its own name, as for example sale, or lacks its own name, for example, I give so that you may give, I do so that you may do, etc.

5. Nude or clothed. A contract is called nude which in the external forum does not beget an obligation, but only an exception ¹: such are agreements which are made without writing or witnesses, as pacts in games, etc. A clothed contract is one which, besides the obligation of conscience, begets an action in the civil forum, as are contracts fortified by the formalities required by law, etc.

¹ If, for example, from a sale I owe you a hundred coins to be paid on the last day of the month, but you promised me that you would give a hundred as a loan; when you seek yours, I can oppose an exception, because that natural obligation of lending survives and has not yet been extinguished.

But nude pacts have other effects also as regards the external forum. For 1. if that which is owed from a pact of this kind has been paid, repetition is not granted; 2. for these natural obligations a surety is bound; 3. the creditor can retain a pledge.

Moreover two pacts are excepted which, although nude, beget an obligation and a civil action, namely: 1. those which, while the simple form of convention remains, have special efficacy of obligation from civil law; these pacts are called legitimate, for example, a pact of donation or of dowry; 2. those which have the same force from praetorian law, as an agreement concerning a pledge. See Vinnius (Ad Lib. 3, Tit. 14, § 2, n. 6).

Likewise in the canonical forum, if the cause pertains to it by reason either of persons or of matter, an action is given for a nude pact of promise, as often as this was entered into with expression of the cause. Indeed expression of the cause is not required if a donation was made to the Church; since a sufficient reason is always presumed, namely the reason of piety and religion. Compare Laymann (Lib. 3, Tr. 4, Cap. 3, n. 3).

6. Formal or express, or virtual or tacit. The former is that which is made by words, writings, or other signs explicitly manifesting consent; the latter, however, is that whose consent to the thing agreed upon indeed exists really, but is manifested only implicitly by some saying or deed. Thus a physician exercising his art is judged to promise that he will do that which his profession requires. This contract is commonly also called a quasi-contract.

7. Absolute or conditioned, according as no condition, or some condition, is placed upon it. It is also called pure or not pure ².

² Add here another partition, according to which some contracts are called of good faith, others of strict right. In the former a judge can arbitrate many things from the equitable and the good; in the latter one must stand by the words of the contracting parties (Lugo, Disp. 22, n. 10). Contracts of good faith are buying, selling, lease, hire, management of affairs, mandate, deposit, partnership, etc. On the contrary, contracts of strict right are considered to be most innominate contracts, and likewise loan for consumption, census, gratuitous stipulation or donation: to this pertains L. 99, ff. De verb. oblig. Whatever belongs to the binding of an obligation, unless it is plainly expressed in words, must be understood as omitted; and we interpret almost always according to the promisor.

755. • In every contract three things must be distinguished, namely essence, nature, and accidentals. 1. To the essence pertain those things without which a contract cannot exist. Thus, for example, in a contract of sale three essential things are given, namely the thing, the price, and consent. One being lacking, there is no contract. If in place of a price, for example, another thing is given, it will no longer be a contract of sale, but of exchange. 2. To the nature pertain those things which, although not expressed, nevertheless from law or custom or equity are understood as comprehended in the contract, although they are not essential; for example, the security furnished against eviction of the thing sold, which could be excluded by the contracting parties without the sale being invalid: when the condition is not expressed, the seller must furnish security for the thing sold. 3. But accidentals are called those things which can be joined to the contract by a special agreement, without being judged added by law or by the nature of the thing; for example, such a delay of price, or other things of this kind. - Bouvier, etc.

These things having been premised, it remains to treat: 1. of the requisites for contracting; 2. of the obligation of a contract; 3. of the modifications of contracts.