The document discusses how banks can create money through the process of making loans. When a bank receives a deposit, it is required to keep a certain percentage, like 20%, as reserves, but can lend out the rest. When those loans are deposited in other banks, they become part of the money supply. This process of successive lending and depositing allows banks to multiply the original deposit. For example, with a 20% reserve requirement, $100,000 in deposits could create $500,000 in the total money supply.