A contract, in legal contemplation, is an agreement between two or more parties, for the doing or the not doing of some particular thing. (a)

It has been said that the word " agreement" is derived from the phrase " aggregatio mentium. " (b) This is at least doubtful, and was probably suggested by the wish to illustrate that principle of the law of contracts which makes an agreement of the minds of the parties or the consent and harmony of their intentions, essential. We shall presently see that they must propose and mean the same thing, and in the same sense.

(a) "A contract is an agreement in which a party undertakes to do, or not to do, a particular thing." Marshall, C. J., Sturges v. Crowninshield, 4 Wheat. 197. - "A contract is an agreement, upon sufficient consideration, to do or not to do a particular thing." 2 Bl. Com. 446. - In Sidenham and Worlington's case, 2 Leon. 224, 225, which was an assumpsit, founded upon an executed consideration, Periam, J., conceived that the action did well lie, and he said there was a great difference between contracts and that case: "For in contracts upon sale, the consideration and the promise, and the sale, ought to meet together, for a contract is derived from con and trahere, which is a drawing together, so as in contracts every thing which is requisite ought to concur and meet together; namely, the consideration, of the one side, and the sale or the promise on the other side. But to maintain an action upon an assumpsit, the same is not requisite, for it is sufficient if there be a moving cause, or consideration precedent, for which cause or consideration the promise was made."

(b) Per Pollard, Serjeant, arguendo in Reniger v. Fogossa, Plowd. 17.

The word " contract " is of comparatively recent use, as a law term. Formerly, courts and lawyers spoke only of "obligations, " (c) - meaning thereby "bonds," in which the word "oblige" is commonly used as one of the technical and formal terms,-"covenants," and "agreements," which last word was used as we now use the word " contract. " The word " promise " is often used in instruments, and sometimes in legal proceedings. " Agreement " is seldom applied to specialties; " contract " is generally confined to simple contracts; and " promise " refers to the engagement of a party * without reference to the reasons or considerations for it, or the duties of other parties.

In the above definition of a contract, no mention is made of the consideration. The Statute of Frauds requires, in many cases, and for many purposes, that the " agreement " shall be in writing, and some note or memorandum thereof be signed by the party sought to be charged. Under this provision, it has been much controverted whether the word " agreement " so far implies a "consideration," that this also must be in writing. This question will be considered in a subsequent part of this work. (d) We have not included the consideration in the definition of the contract, because we do not regard it as, of itself, an essential part thereof. But for practical purposes it is made so by some important and very influential rules, and we shall treat of the consideration as one of the elements of a legal contract.