Why does the business cycle work? It changes all the time, and like any cycle, it always ends where it started. But how? The four parts of the business cycle in order are expansion, peak, recession, and trough. It works because the amount of money the country produces is limited, and affected by so many different things that you could study it your whole life without ever having a full understanding. When we are in a period of expansion, as much as we can want it to continue, it can almost be compared to the weather because every sunny day can only last so long before the occasional cloud rolls through. But like the weather, we can predict almost precisely what the next day will look like. However, some days will always surprise us with something we never would have expected.