"The doctrine of mistake, the same as of fraud, is in the main a product of the more elementary one that parties enter into a contract only by the concurrent consent of their wills to the same thing. If the subject of the contract does not exist; or if the motive to it is a mere illusion, there is, in the one case, a grasp of the wills at vacuity, and, in the other, the wills move falsely."1

In order to render the contract void on the grounds of mistake there must be a mutual mistake, or mistake on one side and fraud on the other. This last class of cases may most properly be considered as falling under the head of fraud. Mistake on one side is not sufficient to void the contract, but a mutual mistake of fact is always a defense. For example, where a contract with a building association was on a written form ordinarily used by the association, which form contained different provision from those agreed on, both parties believing that such form embodied the terms of the contract, and the contract as intended to be made was carried out for over a year, this was sufficient to void the contract on the ground of mistake, and an insistence thereafter by the association that the mortgage and bond was the contract constituted fraud.2 A contract without a consideration as has been frequently shown is void, and this is not altered by the fact that the parties through error believed that there was a consideration. Therefore, if by reason of mistake, there is no consideration for the contract, there is no contract.3 The payment of a debt in counterfeit money or forged paper, does not discharge the debt even although both parties believed it to be genuine,4 but as it is the duty of the officers of a bank to know the signatures of the bank's depositors, if the bank pays to an honest holder the forged check of a depositor, it must suffer the loss.5

Bishop on Contracts, Sec. 693. 2 Home Sav. Asso. vs. Nobleville

Monthly Meeting of Friends' Church, 64 N. E., 478.