A serious question.
The central government lends money to banks, charging interest. The banks lend money to companies and consumers, charging a higher rate of interest. Companies must have credit in order to buy the natural resources necessary to make goods to sell to the people. The companies pay back the banks. But now they owe the banks more money than before. Fair enough, they've made money, so they can afford to pay it back.
But all the money comes from a central source, notably the Federal Reserve in America. They give out all the cash. Then they expect to get back more than they put out. It seems the only way to maintain this kind of system is through bankruptcy - someone along the way has to give all their money to someone, the central cash distribution agency must write off their loan. The amount of money in the system stays equal to the amount given out.
I realise this question may seem laughably simple to many of you, but I am perplexed. I must assume I'm missing something, as a system like that couldn't exist for any length of time.