Sigmund Freud was one of the first people to actually study dreams. He was an active dreamer and believed that dreams were meaningful. After analyzing his own dreams, Freud published The Interpretation of Dreams in 1898.
In the book, he discussed what he believed were two levels of dreams--the "manifest content," which was the actual dream, and the "latent content," which was the hidden meaning behind the dream. He theorized that dreams were wishes people wanted fulfilled and he believed dreams could be interpreted.
