What causes economic bubbles?

During the 1600's, the exotic tulip became a nationwide sensation; some single bulbs even sold for ten times the yearly salary of a skilled craftsman. Suddenly, though, the demand completely plummeted, leaving the tulip market in a depression. What happened? Prateek Singh explains the peak of a business cycle, commonly referred to as a mania. [Directed by Simon Ampel, narrated by Addison Anderson].