U.S. Supreme Court
Grymes v. Sanders, 93 U.S. 55 (1876)
Grymes v. Sanders
93 U.S. 55
1. A mistake as to a matter of fact, to warrant relief in equity, must be material, and the fact must be such that it animated and controlled the conduct of the party. It must go to the essence of the object in view, and not be merely incidental. The court must be satisfied that but for the mistake, the complainant would not have assumed the obligation from which he seeks to be relieved.
2. Mistake, to be available in equity, must not have arisen from negligence where the means of knowledge were easily accessible. The party complaining must have exercised at least the degree of diligence "which may be fairly expected from a reasonable person."
3. Where a party desires to rescind upon the ground of mistake or fraud, he must, upon the discovery of the facts, at once announce his purpose, and adhere to it. If he be silent, and continue to treat the property as his own, he will be held to have waived the objection, and will be as conclusively bound by the contract as if the mistake or fraud had not occurred. This applies peculiarly to speculative property which is liable to large and constant fluctuations in value.
4. A court of equity is always reluctant to rescind unless the parties can be put back in statu quo. If this cannot be done, it will give such relief only where the clearest and strongest equity imperatively demands it. chanroblesvirtualawlibrary