You misunderstood my intent. When borrowed money is paid off, the loan amortizes- dies. A mort-(death)-gage is a loan with death programmed into it. Ther interest being pais is above the principal being returned. The payment of principal kills the borrowed amount on the note... but the interest survives the transaction. That is what I meant by "immortal". It is not snuffed by repayment, but continues as an increased money supply.