This section is from the book "The Law Of Contracts", by William Herbert Page. Also available from Amazon: Commercial Contracts: A Practical Guide to Deals, Contracts, Agreements and Promises.
At the same time, it will not be presumed that the creditor intended to substitute one cause of action for another, unless it appears to have been the intention of the parties to accept the promise of the debtor as satisfaction. The original cause is not discharged by an executory accord,10 and in such case the debtor can not make it operate as a discharge by tendering performance of the accord after action has been brought on the original cause of action.11
The position which is intermediate between the original rule that an executory accord had no legal effect, and the modern rule that the promise of the debtor may be a satisfaction of the original liability if the parties so agree, is found in some jurisdictions in which it is said that the accord is to be regarded as executed when the debtor has performed as far as he has agreed to perform,12 or when he has performed the accord to the point at which it is to operate as a satisfaction of the original liability.13 Accordingly, a composition deed is held to operate as a discharge to the original liability where the debtor has performed the terms of such composition deed on his part.14