This section is from the book "The Law Of Contracts", by William Herbert Page. Also available from Amazon: Commercial Contracts: A Practical Guide to Deals, Contracts, Agreements and Promises.
The agreement which results in obligation and which amounts to a contract is distinguished at our law from mere intent. It would be difficult to construct a system of law in which obligation could attach to the intention of a party without any declaration of such intention on his part; but a system of law might be imagined in which a unilateral declaration of intention might be given legal effect. As far as such rights are recognized at our law, they are treated as property rights rather than as contracts. The intention which our law recognizes and enforces as the basis of a contract, is the promise.
Except in the possible case of the promise under seal, a promise creates no obligation until acceptance by the promisee. While it might be possible to attach obligation to an unaccepted promise, such a form of liability is contrary to common-law notions. In fact, at common law an accepted promise creates no obligation unless it is under seal or unless it is supported by a valuable consideration.1 Statements are occasionally found to the effect that agreement and contract are synonymous terms.2 Probably the existence of obligation was assumed in these cases; and it was not intended to say that every agreement, whether enforceable or not, was a contract.