The immediate cause of the increase of population is the excess of the births above deaths; and the rate of increase, or the period of doubling, depends upon the proportion which the excess of the births above the deaths bears to the population.
Thomas MalthusWhere are we to look for the consumption required but among the unproductive labourers of Adam Smith?.
Thomas MalthusPopulation, when unchecked, goes on doubling itself every 25 years or increases in a geometrical ratio.
Thomas Malthus