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.
An offer may be withdrawn before acceptance by acts of the offeror, inconsistent with the continued existence of the offer, and properly brought to the knowledge of the offeree.1 A common example of such revocation is found in offers of sale, where the offeror sells the property in question to another person before the offer is accepted, and the offeree receives due notice of such sale before acceptance.2 Thus A offered to B to sell a mortgage for less than the amount due. Before definite acceptance A notified B that he had sold the mortgage to a third person. This was equivalent to a withdrawal of the offer.3 If such notice is given by the offeror or his agent to the offeree or his agent, it is as clear and unequivocal a revocation as could be made by any form of words. If the offeree's knowledge is received through third persons, a different and more difficult question arises, which is discussed elsewhere.4