Rescission, when not effected by consent, can be accomplished only by the use, on the part of the party rescinding, of reasonable diligence to comply with the following rules:
1. He must rescind promptly, upon discovering the facts which entitle him to rescind, if he is free from duress, menace, undue influence, or disability, and is aware of his right to rescind; and, 2. He must restore to the other party everything of value which he has received from him under the contract; or must offer to restore the same, upon condition that such party shall do likewise, unless the latter is unable, or positively refuses to do so.
R.L.1910, § 986.