In which John Green teaches about filthy, filthy lucre. Money. And Debt. So, what is money? And what is it for? And why do we use money? And why does it all disappear so quickly after payday? John will look into 75% of these questions, and if he doesn't come up with answers, we'll get into some interesting ideas along the way, at least. This week we'll investigate whether money displaces barter, then leads to war, slavery, and what we think of as civilized social orders. We'll also see what old Adam Smith thinks of big money, no whammies, this week on Crash Course.