Mr. Chief Justice Bean
delivered the opinion.
The demurrer was properly sustained. The instrument sued on is not a contract. There is no mutuality, and it is not sup*611ported by any consideration. It is merely a written offer by the defendant Schotte to sell the land therein described to the plaintiff at any time within the period stated, and was subject to revocation prior to acceptance: Bishop, Contracts, § 325; Wharton, Contracts, § 10; Gordon v. Darnell, 5 Colo. 302; Dickinson v. Dodds, L. R. 2 Ch. Div. 463; Litz v. Goosling (Ky.) 21 L. R. A. 127, note. It was capable of being converted into a valid contract by the tender of the purchase money within the time stated and before its withdrawal by Schotte: Boston & Maine R. Co. v. Bartlett, 3 Cush. 224. But, until such acceptance, there was no contract which could affect the title to the land or give the plaintiff vested rights therein: Mers v. Franklin Ins Co. 68 Mo. 127; 21 Am. & Eng. Enc. Law (2 ed.), 925. Where an offer like the one in question is accepted, the minds of the parties meet and the contract becomes complete and binding on the giver of the option and all who claim from him with knowledge thereof, and may be enforced against them: Ross v. Parks, 93 Ala. 153 (8 South. 368, 11 L. R. A. 148, 30 Am. St. Rep. 47); Haughwout v. Murphy, 22 N. J. Eq. 531; Barrett v. McAllister, 33 W. Va. 738 (11 S. E. 220). But, until acceptance, it imposes no obligation whatever on either party, and is subject to revocation. The sale of the land by Schotte to the lumber company, as appears from the complaint, was made prior to the acceptance of the offer by the plaintiff and before there was any contract for the sale of such land. The plaintiff, therefore, had at the time no interest in the property, legal or equitable, which he could enforce against Schotte or a purchaser from him. It is unnecessary to consider whether the sale operated as a revocation or withdrawal of the offer. If it did not, and the subsequent acceptance by the plaintiff, without knowledge of such sale, converted the proposal into a valid contract between him and Schotte, such contract would not relate back and affect the title of the land at the time of the sale to the lumber company.
The decree is affirmed. Aeeirmed.