11-13. In General.

14-15. Communication by Conduct - Implied Contracts.

16. Communication of Offer.

17. Necessity and Effect of Acceptance. 18-20. Communication of Acceptance.

21. Character, Mode, Place, and Time of Acceptance.

22-23. Revocation of Offer.

24. Lapse of Offer.

25. Offers to the Public Generally.

26. Offer as Referring to Legal Relations.

In General

11. To constitute a contract, the expression of common intention must generally, if not always, arise from an offer made by one party to another, and an acceptance by the latter, with the result that one or both are bound by a promise.

12. The offer may be -

(a) Of a promise, or

(b) Of an act.

13. The acceptance may be -

(a) Simple assent; but this applies to contracts under seal only.

(b) Giving of a promise.

(c) Doing of an act.

In practical matters, and for the purpose of creating obligations, every expression of a common intention arrived at by two or more parties is ultimately reducible to question and answer, or to offer and acceptance.1 Thus, if a person agrees to sell an article to another for a certain price, and the latter agrees to buy it, we can trace the process to the moment when the seller says in words or by conduct, "Will you give me so much for the article?" and the buyer replies, "I will;" or when the buyer says, "Will you take so much for the article?" and the seller says, "I will." There is always this question and answer, or offer and acceptance, though in many cases it is not in so many words. A tradesman displaying his goods says in act, though not in words, "Will you buy my godds at my price?" and a customer taking goods with the tradesman's cognizance virtually says, "I will." The proprietor of a public conveyance, by running it in such a way and place as to invite people to use it, virtually says, "Will you pay me the fare if I carry you?" and one who gets into the conveyance to be carried, by his conduct says, "I will," as plainly as if he were to use the words. And so all contracts, or voluntary obligations, may be reduced to question and answer, either in words, or by conduct, or both. The question is the offer; the answer the acceptance of the offer.

1 Anson, Cont. (4th Ed.) 11; Leake, Cont. 12; Thruston v. Thornton, 1 Cush. (Mass.) 91. Pollock objects that this analysis does not properly apply to a case in which the consent of the parties is declared in a set form, - as where they both execute a deed or sign a written agreement. Pol. Cont. 4. But he adds that, "notwithstanding the difficulties that arise in making proposal and acceptance necessary parts of the general conception of contract, there is no doubt that in practice they are the normal and most important elements." Id. 8. See "Contracts," Dec. Dig. (Key-No.) § 16; Cent. Dig. §§ 49-56, 71-92.

A written contract, the terms of which have been agreed upon by the parties, but which they have further agreed is to become binding only upon its execution and delivery, is an apparent exception to the above rule that every contract originates in an offer and acceptance. But the delivery of the written instrument by one party, either in person or through his agent, may be said to constitute an offer, and its receipt and approval by the other party an acceptance.