Illinois holds that if the parties proceed to execute fully the modified agreement, so that nothing remains to be done by either party and it is no longer executory, the contract as executed will not be disturbed; that, so long as the modified agreement remains executory, the party waiving the greater amount and accepting the lesser has a right to repudiate the agreement and claim the full amount specified in his original contract; that while the modified agreement remains executory, one may rightfully demand full payment of the specified payments, but that, having the right to waive performance of the original agreement and carry the modified contract into effect, if he does so and fully performs and accepts the benefit of the new agreement, he cannot thereafter repudiate it and sue for the larger sum. Snow v. Griesheimer, 220 Ill. 106, 77 N.E. 110; Doyle v. Dunne, 144 Ill. App. 14; Levy v. Greenberg, 261 Ill. App. 541. Cases from other jurisdictions supporting this are Romaine v. Beacon Lithographic Co., 13 Misc. 122, 34 N.Y.S. 124; State v. American Surety Co., 137 Or. 394, 300 P. 511, 2 P.2d 1116; Julian v. Gold, 214 Cal. 74, 3 P.2d 1009, 1010; Nordfors v. Knight et ux., 90 Utah 114, 60 P.2d 1115; Price v. Price, 24 Cal.App.2d 462, 75 P.2d 655; Bishop on Contracts, 2d Ed. 37; Idaho Gold Dredging Corp. v. Boise Payette Lumber Co., 62 Idaho 683, 115 P.2d 401; 17 C.J.S., Contracts, ยง 376, p. 862.
The jury accepted appellee's contention in this respect and returned its verdict in his favor. This court in that case permitted the contention of appellee that the reduced monthly payments had been accepted by appellant in lieu of the rental agreed upon, to stand, on the theory that each of them constituted an executed agreement ( Levy v. Greenberg, 261 Ill. App. 541); but that when appellee abandoned the premises on June 2, 1933, without the payment of the rent for that month, that he, by the terms of the lease, was obligated on the date of the judgment for the rental for that month, as provided for in the lease, the lease not having then expired. The judgment of the circuit court was reversed and judgment entered in this court in favor of appellant and against appellee for the amount of $175 as rental for the month of June, 1933, as provided for under the terms of the lease, together with appellant's attorney fees as provided by said lease.