An agreement is an expression by two or more persons of assent in regard to some present or future performance by one or more of them.4 Agreement is in some respects a wider term than contract. It covers executed sales, gifts, and other transfers of property. It also covers promises to which the law attaches no legal obligation. An agreement is essential for the formation of a simple contract, but is not the only requisite. On the other hand, the common law recognized the possibility of contractual liability under a formal contract by the mere act of the obligor-that is, without agreement.5 cerned. Harriman on Contracts (2d ed.), Sec. 623. It is doubtless true that the early conception of a sealed contract was analogous rather to a grant or to a conclusive statement of fact made in such fashion that the obligor could not dispute its correctness than to a promise, but in quite early times the validity of a covenant under seal in terms promising to do an act in the future was recognised, and it must have been very long ago when the conception of the meaning of such a covenant became substantially that which would be entertained to-day. At the present time even though a contract under seal be in the form of an acknowledgment of an existing indebtedness, it is clear enough that the language means in fact to the parties,-as it means in law-a promise. In defining what is a contract it must be remembered one is not explaining history, but analysing the meaning of the word to-day.
3"The act alone is the contract, the resulting contractual relation is quite a different thing." Holland, Jurisprudence (10th ed.), p. 261.
Professor Corbin defines contract, it is true, as "the legal relations between persons arising from a voluntary expression of intention, and including at least one primary right in personam, actual or potential, with its corresponding duty," (26 Yale L. J. 170), but the terms of a contract do not necessarily include all the rights and duties which the law imposes when the contract is formed. See infra, Sec. 615; and in any event the words contractual obligations and rights sufficiently express the relations between the parties.
4See Carter v, Prairie Oil & Gas Co. 58 Okl. 365, 160 Pac. 319.
5 See infra, Sec. 205.