was forbidden in India), opposed taxes encouraging emigration, and believed in restricting asceticism to the aged. In ancient Greece, Plato (427-347 BC) and Aristotle (384-322 BC) discussed the best population size for Greek city-states such as Sparta, and concluded that cities should be small enough for efficient administration and direct citizen participation in public affairs, but at the same time needed to be large enough to defend themselves against hostile neighbors. In order to maintain a desired population size, the philosophers advised that procreation, and if necessary, immigration, should be encouraged if the population size was too small. Emigration to colonies would be encouraged should the population become too large. Aristotle concluded that a large increase in population would bring, "certain poverty on the citizenry and poverty is the cause of sedition and evil." To halt rapid population increase, Aristotle advocated the use of abortion and the exposure of newborns (that is, infanticide). Confucius (551-478 BC) and other Chinese writers cautioned that, "excessive growth may reduce output per worker, repress levels of living for the masses and engender strife." Confucius also observed that, "mortality increases when food supply is insufficient; that premature marriage makes for high infantile mortality rates, that war checks population growth." Ancient Rome, especially in the time of Augustus (63 BC-AD 14), needed manpower to acquire and administer the vast Roman Empire. A series of laws were instituted to encourage early marriage and frequent childbirth. Lex Julia (18 BC) and the Lex Papia Poppaea (AD 9) are two well-known examples of such laws, which among others, provided tax breaks and preferential treatment when applying for public office for those who complied with the laws. Severe limitations were imposed on those who did not. For example, the surviving spouse of a childless couple could only inherit one-tenth of the deceased fortune, while the rest was taken by the state. These laws encountered resistance from the population which led to the disregard of their provisions and to their eventual abolition. Tertullian, an early Christian author (ca. AD 160-220), was one of the first to describe famine and war as factors that can prevent overpopulation. He wrote: "The strongest witness is the vast population of the earth to which we are a burden and she scarcely can provide for our needs; as our demands grow greater, our complaints against Nature's inadequacy are heard by all. The scourges of pestilence, famine,