A more difficult case arises where the defence does not relate to the origin of the contract, but is based on supervening circumstances, such as non-performance by the promisee of a counter promise made by him, or discharge by the promisee by release or rescission. The defence of non-performance should be available against the third person whether he is a sole beneficiary or a creditor of the promisee. The defence is properly based on failure of consideration.3a As the substantial matter the parties had in mind was the performance of the. promises the defendant promisor has in substance not received what he bargained for. Under these circumstances it is unjust to allow a mere donee to enforce the promise; and if the third person is a creditor he is not entitled to any greater right than his debtor had.4