Policies of insurance invariably contain provisions to the effect that, upon occurrence of the event insured against, notice thereof shall be given to the insurer. As in the normal contract, such condition qualifies the undertaking of the promisor unless its performance is legally excused. In actions for breach of promise, impossibility of performance has been held to constitute a good defense to the suit for damages in certain instances, though the early rule was that payment of damages was never impossible and hence impossibility of performance was no defense in an action for breach. It is to be noted that if impossibility will excuse the performance of a condition, it operates differently in that it does not give a defense as in the cases of inability to perform a promise, but gives the party who has failed to perform the condition a right of action against the other for breach of promise. There is authority for this result in contracts other than insurance policies.