Having ascertained the particular features of contract as a juristic conception, the next step is to ascertain how contracts are made. A part of the definition of contract being that it is an agreement enforceable at law, it follows that we must analyze the elements of a contract such as the law will hold to be binding between-the parties to it.
10. As there must be an agreement directly contemplating and resulting in an obligation, and the agreement must be enforceable in the law, therefore -
(b) The agreement must possess the marks which the law requires in order that it may affect the legal relations of the parties, and be an act in the law. Therefore -
(1) It must be in the form required by law.
(2) There must be a consideration, when required by law.
(c) The parties must be capable in law of making a valid contract.
(d) The consent expressed in offer and acceptance must be genuine.
(e) The objects which the contract proposes to effect must be legal.31
Where all of these elements coexist, a valid contract is the result. If any one of them is absent, the agreement is in some cases merely unenforceable; in some voidable at the option of one of the parties; and in some absolutely void. We shall now take up in turn each of these elements in separate chapters.
31 Justice v. Lang, 42 N. Y. 493. 1 Am. Rep. 576. See "Contracts," Dec. Dig. (Key-No.) § 103; Cent. Dig. §§ 468-476.