Chapter I — The definition of a contract, its causes and properties

I. QUESTION I. What is a contract? ANSWER. The common notion of it is assigned thus. It is the deliberate consent of a twofold will, of the giver and of the receiver, concerning some thing to be done or not done, manifested by some exterior sign. Four things therefore are required in any absolute and perfect contract. The first is the declared consent of that twofold will. The former will is called offering, provoking, and challenging; the latter receiving, provoked, and challenged. The seller's will offers and provokes; the buyer's will is receiving and provoked — although sometimes the buyer offers and provokes. The second is the conjunction of that twofold will. The third is obligation. The fourth is the efficacious action by which each contracting party fulfils his own debt. And so the contract is prior to the obligation, and this precedes the action. The obligation and the action are of two kinds: the one civil, the other natural. The civil needs the proof either of records, or of a bond, or of a written instrument. The natural is content with the testimony of the mind and of conscience. And so in any contract a twofold form can be regarded. The first is essential, which always and everywhere among all nations obtains. The other is adventitious, or accidental, which is constituted in the law of some people or prince. Of the four prerogatives recounted, the first two pertain to the form of the contract: for a contract, strictly taken, is a mutual convention concerning something to be done. This reciprocal concord of wills obligation follows, as a formal effect.

II. The proximate matter of a contract is human acts pertaining to justice. All contracts are reduced to these four: I give that you may give; I give that you may do; I do that you may give; I do that you may do. While contracts of this kind are committed to execution, they put on some determinate species or form. And this is exceedingly to be noted for the forestalling of frauds and usuries.

III. Conrad assigns thirty species of contracts, which partition Fr. Dominic Soto disapproves, who digests the named contracts into three orders, and reduces them to seven species. The first order is of those by which dominion is transferred; the second of those by which the usufruct; the third of those by which the use. In the first order he places liberal donation, exchange, buying, selling, and lending. In the second, emphyteusis. In the third, loan for use, letting, and hiring. From the species of contracts he removes deposit, pledge, and suretyship.

IV. The first contract approved in the holy Scriptures is that of matrimony. Others are contracts approved in general, as is gathered from the Apostle, 1 Thessalonians 4, where it is said: That no man overreach nor circumvent his brother in business. The contract of loan is clearly commended in Luke 6: Lend, hoping for nothing thereby. The contract of letting is declared in the parable of the vineyard let out to murderous and criminal husbandmen, Luke 20; and the contract of hiring in the other parable concerning the labourers hired. The contract of buying is recounted in Genesis 47, where Joseph bought the estates of Egypt, and let out the same to the Egyptians themselves at a fixed agreed rent.

V. QUESTION II. How are contracts perfected? ANSWER. In any contract a twofold perfection is distinguished: one substantial, the other adventitious. The former is had when all those things are added which are necessary to the species of the contract. Thus a sale is perfect as regards its species as soon as it has been agreed between buyer and seller concerning the price. But by the delivery of the ware it is perfected accidentally and as regards the integrity of the contract. In four ways contracts are wont to be perfected. By consent declared by an exterior sign. By words, or a determinate form of words. By writing, when it is necessarily required. By delivery of the thing, without which some contracts are not completed. By consent are perfected those contracts which signify a mutual convention of the contracting parties, as are buying, selling, letting, hiring: writing, or the instrument which the contracting parties draw up after the mutual convention, is required not for the nature but for the proof of the contract. Other contracts demand a determinate form of words, as in a stipulation, in which, one asking: Do you promise me? the other replies: I promise. Will you give me? I will give. Which form of words, although it once obtained among the Romans, has now wholly grown obsolete, and it is enough that the consent of the contracting parties be proved by any words whatsoever. By writing are perfected emphyteusis and other contracts which, before they be written by a notary, have no force, custom or law so obtaining. The contracting parties can also suspend their consent until the writing be drawn up. By delivery of the thing are perfected loan, donation, loan for use, deposit, exchange, pledge. These before delivery are not reckoned perfect, but bare agreements.

VI. If contracting parties celebrate contracts with outward words without an inward mind of contracting, the contract is null: although in the exterior forum the deceiver is deservedly compelled to fulfil the contract, because consent is presumed. Nay, in the interior forum also the deceiver is bound to give consent. In few words I will touch upon the nature of obligation.

VII. Obligation is the bond by which a man binds himself to furnish something. Among these, one is friendly, resting upon the honourableness of the thing, by which a man is grateful to his benefactor; the debt of this is moral, not a precept of justice. Another obligation is founded in a commanding law, and is called a legal debt, which can arise either from charity, or from religion, or from justice, or from obedience. Obligation proceeding from justice alone brings in the debt of restitution. Obligation flowing from justice is either merely natural, which binds in the forum of conscience, but in the exterior forum gives no action; or merely civil, when according to what is alleged and proved a man is convicted a debtor who in truth is not, and is compelled to pay; or it is at once natural and civil, which binds in each forum.