This is a suit by an indorsee against an indorser of a small promissory note. The plaintiff not having presented the note to the promisor when due, nor given any notice to the indorser, relied on a waiver by an after promise to pay, with notice that no demand had been made or notice given. We think the directions were right. The legal foundation of the doctrine of waiver is, that a party knowing his *163rights, voluntarily consents to forego them, and not insist on them. Knowledge of all the material facts on which those rights depend, is essential to a valid waiver. The legal liability of an indorser is conditional on demand and notice. But the condition is one made for his benefit, and therefore he may waive it. If he is satisfied that demand and notice would be of no benefit to him, it is quite natural that he should waive them. In general, if he knows there has been no demand and notice, and yet promises to pay, it is strong evidence of waiver. But if there be other facts which might tend to influence his judgment, known to the holder, but not to the indorser, then his promise to pay is not conclusive evidence. Here then were facts alleged to be material, and if true were so, and they were left to the jury, with proper directions, who found a verdict for the defendant, and therefore affirmed the truth of the facts. Exceptions overruled.