His first born Henry became vicar of Effingham, Surrey in 1835 and of Donnington, Sussex in 1837; he married Sofia Otter (1807–1889), daughter of Bishop William Otter and died in August 1882, aged 76. His middle child Emily died in 1885, outliving her parents and siblings. The youngest Lucille died unmarried and childless in 1825, months before her 18th birthday. Malthus argued in his "Essay" (1798) that population growth generally expanded in times and in regions of plenty until the size of the population relative to the primary resources caused distress: Malthus argued that two types of checks hold population within resource limits: "positive" checks, which raise the death rate; and "preventive" ones, which lower the birth rate. The positive checks include hunger, disease and war; the preventive checks: birth control, postponement of marriage and celibacy. The rapid increase in the global population of the past century exemplifies Malthus's predicted population patterns; it also appears to describe socio-demographic dynamics of complex pre-industrial societies. These findings are the basis for neo-malthusian modern mathematical models of "long-term historical dynamics". Malthus wrote that in a period of resource abundance, a population could double in 25 years. However, the margin of abundance could not be sustained as population grew, leading to checks on population growth: In later editions of his essay, Malthus clarified his view that if society relied on human misery to limit population growth, then sources of misery ("e.g.", hunger, disease, and war) would inevitably afflict society, as would volatile economic cycles. On the other hand, "preventive checks" to population that limited birthrates, such as later marriages, could ensure a higher standard of living for all, while also increasing economic stability. Regarding possibilities for freeing man from these limits, Malthus argued against a variety of imaginable solutions, such as the notion that agricultural improvements could expand without limit. Of the relationship between population and economics, Malthus wrote that when the population of laborers grows faster than the production of food, real wages fall because the growing population causes the cost of living ("i.e.", the cost of food) to go up. Difficulties of raising a family eventually reduce the rate of population growth, until the falling population again leads to higher real wages. In the second and subsequent editions Malthus put more emphasis on "moral restraint" as the best means of easing the poverty of the lower classes."