What is money, and where does it come from? What does the monetary system have to do with sustainability? In this lecture, I explain what money is, and how it is created and destroyed by commercial banks. I look at some of the criticisms of our current monetary system, and discuss possible alternatives, such as Sovereign Money Creation and a Sovereign Money System. Lastly, I explore the links between money creation and environmental sustainability, including the tough question of whether our current monetary system creates a dangerous growth imperative.