Distinction between Civil Obligation and Natural Obligation

      A civil obligation(as defined in Art. 1156) is based on positive law; hence, it is enforceable by court action.

      A natural obligation  on the other hand, is based on natural law; hence, it is not enforceable by court action. The obligation, however, exists in equity and moral justice, such that if the debtor voluntarily performs it, he can no longer recover what he has given.

      Illustration:

      Molly is the maker of a promissory note with Polly as the payee for Php200,000.00. If Molly does not pay on due date, Polly can enforce payment by filing a court action. If Polly does not file a court action against Molly within 10 years from due date which is the prescriptive period for actions upon a written contract, Polly losses the right to enforce payment by court action. However, if Molly voluntarily makes the payment to Polly although the obligation has prescribed, Molly will no longer be allowed to recover the payment because in equity and moral justice, she still owed Polly the amount of Php200,000.00.