"His fame grew with the publication of a vastly expanded second edition in 1803, which substantiated the basic principle of population with references to 18th-century travel literature and statistics gleaned from the latest censuses, but which also elaborated on a moral dimension of the Essay’s otherwise abstract, mechanical reasoning. To the positive checks of war, famine and pestilence Malthus added the ‘preventive’ check of moral restraint – man’s unique capacity to abstain from ‘promiscuous intercourse’, save money and delay marriage. This exception to the otherwise implacable laws of nature signalled an anthropological turn in Malthus’s argument, but also, as the historian Boyd Hilton put it, an ‘evangelical creep’."

https://www.lrb.co.uk/the-paper/v46/n18/oliver-cussen/prophet-of-the-past