Money is created when banks lend it into existence. When a bank provides you with a $100,000 mortgage, it creates only the principal, which you spend and which then circulates in the economy. The bank expects you to pay back $200,000 over the next 20 years, but it doesn't create the second $100,000 - the interest. Instead, the bank sends you out into the tough world to battle against everybody else to bring back the second $100,000.
***Bernard Lietaer