Economies, companies, and markets operate according to patterns or cycles. These cycles arise from naturally occurring phenomena in everyday business, and to a large extent from the simple ups and downs of human psychology and behavior. When should you pull out of the market? When should you stay in? These fundamental psychological influences -- including greed and fear -- can and do profoundly affect investors. If you carefully study past cycles, understand their origins and import, and remain alert for the next up or down cycle, you won't have to reinvent the wheel in order to understand every investment environment. And you're less likely to be blind-sided by unexpected events. Howard Marks, cofounder of Oaktree Capital Management, provides insights to help you master these recurring patterns for your own financial gain and psychological benefit.