Thomas Robert Malthus, the English economist and moral philosopher, is most famous for his contributions to population studies. In his Principles of Political Economy (1820) and in his controversies with David Ricardo, Malthus seems partly to have anticipated J. M. Keynes; and Keynes himself, in his Essays in Biography, generously remarked that "if only Malthus, instead of Ricardo, had been the parent stem from which nineteenth century economics proceeded, what a much wiser and richer place the world would be today!"

Malthus's work on population is contained in two books, misleadingly presented as if they were merely different editions of one. The first, best referred to as the First Essay, is actually titled An Essay on the Principle of Population as It Affects the Future Improvement of Society, with Remarks on the Speculations of Mr. Godwin, M. Condorcet, and Other Writers. The second...