in an expression of their common will, designed to regulate their legal relations."3 § 5. Bilateral and Unilateral Contracts. If the agreement makes both parties creditors and debtors, promisors and promisees, in turn one of the other, we have what is called a bilateral contract-there is a promise on each side. If on the other hand, one party only becomes debtor or promisor, so that nothing can be demanded by virtue of the contract from the other party, the agreement is unilateralthe promise is ex uno latere. Contracts of sale, hiring or for future work are examples of bilateral contracts. Contracts of loan and depositum and those which impose an obligation on one party only are unilateral. $ 6. Requisites of a Contract. The essential elements of a valid contract are these: 1. The consent or agreement of two persons. The consent must be communicated between the two or manifested in some external manner. This subject is treated in the next chapter under the head of Offer and Acceptance. 2. A definite or ascertainable object which constitutes the subject-matter of the agreement. This is considered in the next chapter under the head of Certainty. 3. The agreement must either be based upon a consideration or be expressed in the solemn form prescribed by law. These requisites are dealt with in the chapters relating to Consideration and Form. 4. The person who makes the promise must be legally capable of entering into that particular kind of contrart. This is considered in the chapter relating to Capacity of Parties. 3 The preceding sections have been based in part on Windscheid's Pandektenrecht, §§ 43, 63, 251; Puchta's Institutionem, § 251; Demolombe, Contrats, vol. i, ch. i. 5. The consent of the parties and its outward expression must be real and genuine. The promisor must have meant what he said and his manifestation of consent must not have been extorted by fear or fraud or error. These requisites are considered in the chapters dealing with mistake, misrepresentation, fraud, duress and undue influence. 6. The subject matter of the agreement must be one which the law permits to be accomplished. This is treated in the chapter relating to Legality of Object. PART II REQUISITES OF A CONTRACT CHAPTER I AGREEMENT-OFFER AND ACCEPTANCE § 7. In General-Necessity of Offer and Acceptance. The first requisite of a valid contract is the agreement of two persons in willing the same thing, their consent, the meeting of their minds. It is obvious that there can be no agreement unless there be some external act manifesting and communicating the common purpose of the parties; the outward and visible sign of their inner will. The purpose of the one must be communicated in some manner to the other, who in turn must indicate that his purpose corresponds with that communicated to him. This accord of two wills is not brought about by two persons simultaneously expressing precisely the same intention. In a contract, one person promises to do some one thing, or shows that he intends to do it, and the other person exhibits his agreement and consent, not by expressing his purpose to do the same thing himself, but by expressing his willingness or expectation that the proposer shall do the thing offered. If the proposer asks by his offer that something be done by the other person in turn, then the latter assents by his promise to do that thing, or by his actually doing it. The initiative must needs be taken by one of the parties. who makes a certain proposal or offer to the other, thus asking him to unite in creating an obligation. The offer is the first step in the formation of a contract, the first link in the legal chain which constitutes the obligation. If the other accepts this offer and expresses an analogous purpose, the parties are agreed, their wills have coalesced, they have come together and made a convention (convenire). Numerous offers and counter offers may be exchanged before finally the offer of one party is met by an unqualified acceptance of the other, and the initiative may have been taken by the party who becomes the promisee. Offer and acceptance are then the two essential and inseparable elements of consent. "Every agreement begins with an offer and is completed by an acceptance. Suppress one of these elements and you have absolutely nothing. An offer unaccepted is a sterile act, powerless to create a right, and an acceptance without a preliminary offer is an impossible and absurd notion."1 When a landlord and tenant sign at the same time a lease which has been prepared for them, that transaction has been preceded by an offer from the one or the other and its accept ance. Agreement is the reciprocal manifestation of the complete accord of two or more persons for the purpose of binding each to a performance towards the other, or for the purpose of binding one only to the other, who accepts without himself assuming any corresponding obligation. Consent therefore is never an unilateral fact. The contract may be unilateral, but the cause must not be confounded with the effect, that is to say, the agreement with the contract. Even when the contract binds one person only, the agreement which created it must have been bilateral, for the simple reason that no promise binds the promisor unless it is accepted by the promisee. The apparent exception in the case of an absolute promise under seal is to be explained by the circumstance that acceptance is presumed until the offeree declares his dissent. To the definition of contract as an agreement creating an obligation, it has been objected that there are certainly some valid contracts which do not create obligations, as for instance, an agreement to rescind or discharge a pre-existing contract, in which case, there is no bringing together of the parties but rather a putting of them asunder; or a sale for cash, as when one takes a book from a stall at the same time 1 Larombiere (Oblig.), i, 6, 2 Giorgi, Teoria delle Obbligazioni, vol. iii, n. 138. |