Thomas Robert Malthus was an English cleric and scholar best known for his theories on population growth and its relationship to resources, particularly food supply. His ideas, articulated in his influential work 'An Essay on the Principle of Population' published in 1798, highlighted the potential for population growth to outpace food production, leading to famine and societal issues. Malthus's theories became a significant part of economic thought during the period of change from 1648 to 1815, especially regarding the relationship between population dynamics and economic development.