The basic premise of the series is that the Ethicals, scientifically advanced superhumans from the distant future, have resurrected along the banks of a meandering river on an artificial planet all thirty-six billion people — excluding the retarded and those who died under the age of five — who lived on Earth from 99,000 BC to AD 1983. The resurrectees are given twenty-fiveyear-old naked bodies entirely free of blemish and disease, and provided with all the necessities of life. This imaginary framework allows Farmer to isolate, as if in a laboratory, two fundamental human motivations: the erotic and the hunger for power. As the great majority of Riverworld's inhabitants quickly turn to their old destructive behavior of Earthly life, they pass from Eden to barbarism to industrialization, with all its attendant problems. Instead of cooperating in their attempt to reach the Ethicals' tower at the mouth of the...