An Essay on the Principle of Population
Spencer's work also served to renew interest in the work of Malthus. While Malthus's work does not itself qualify as social Darwinism, his 1798 work "An Essay on the Principle of Population", was incredibly popular and widely read by social Darwinists. In that book, for example, the author argued that as an increasing population would normally outgrow its food supply, this would result in the starvation of the weakest and a Malthusian catastrophe.