Consideration is the thing or act of value, given to or done for, one party to a contract, or promise made to him at his request, either express or implied, in return for the thing given, act done, or promise made on his part.

This definition although somewhat different from those often given, is believed to be the only correct one. A common definition is something like the following: "Consideration is that which moves from the promisee or to the promisor at the express or implied request of the latter in return for a promise." Such, a definition would give the idea that there was a consideration only on the one side of the contract. In every contract, there must be a consideration on both sides, the act or promise on the one side being the consideration for the act or promise on the other. The general classes of this kind of consideration are outlined in the following words in the work which is the greatest recent addition to American legal literature: "With the death of Elizabeth (1603) the formative period in the history of consideration came to a close and English contract law was ready to enter upon its modern career. It will be noted that several forms of consideration had now appeared. First in importance is that detriment to the promisee, (1505) which is necessary to give validity to the simple unilateral promise. This is the original form of the assumptual consideration and is the type into which all other forms of consideration are commonly but erroneously supposed to be resolvable. Next in importance is the consideration of mutual promises. (1588.) Least notable of the three different types of the assumptual consideration is the consideration of legal duty or precedent debt (cir. 1550).

"It is not possible by any valid process to resolve these different sorts of consideration into one. No present detriment to the promisee is found either in the consideration of legal duty or in mutual promises. In the one case the detriment is past, having been incurred when the debt was created. In the other there is a contemplated detriment to both parties, i. e., future performance of the respective promises; but the contract is valid from the time the mutual promises are made. It is indispensable to consideration in the sense of detriment that the detriment should concur with the promise.

"Of the recompense, or benefit, to the grantor of real property, which is necessary to pass the use in equity to a stranger; and of love and affection, which is sufficient to support a covenant to stand seized to the use of one closely related by blood or marriage, we take no further account, as these are not assumptual considerations." 1

A mere benefit to the promisor where there are no mutual promises and no detriment to the promisee is not a sufficient consideration to support the promise.