One day, because they realize for some reason or other that...

One day, because they realize for some reason or other that they must stop credit expansion, the banks do stop creating new credit to lend. Then the firms that have expanded cannot get credit to pay for the factors of production necessary for the completion of the investment projects which they have already committed themselves. Because they cannot pay their bills, they sell off their inventories cheap. Then comes the panic, the breakdown. And the depression starts.