The behavior of a search engine, when not actively conducting a search, resembles the activity of a dreaming brain. Associations made while “awake” are retraced and reinforced, while memories gathered while “awake” are replicated and moved around. William C. Dement, who helped make the original discovery of what became known as REM (rapid eye movement) sleep, did so while investigating newborn infants, who spend much of their time in dreaming sleep. Dement hypothesized that dreaming was an essential step in the initialization of the brain. Eventually, if all goes well, awareness of reality evolves from the internal dream—a state we periodically return to during sleep. “The prime role of ‘dreaming sleep’ in early life may be in the development of the central nervous system,” Dement announced in Science in 1966.