The influence of Malthus' theories was substantial. Among others, he developed a theory of demand-supply mismatches which he called "gluts." Considered ridiculous at the time, as it violated Say 's Law which basically stated that supply creates its own demand, his theory was a precursor to later theories about the Great Depression, and to the works of admirer and economist John Maynard Keynes . Malthus has also been admired by, and has influenced, a number of other notable economists, including David Ricardo with whom he maintained a long lasting friendship but opposite thinking on economics.
In the course of this enquiry I found that much more had been done than I had been aware of, when I first published the Essay. The poverty and misery arising from a too rapid increase of population had been distinctly seen, and the most violent remedies proposed, so long ago as the times of Plato and Aristotle. And of late years the subject has been treated in such a manner by some of the French Economists; occasionally by Montesquieu, and, among our own writers, by Dr. Franklin, Sir James Stewart, Mr. Arthur Young, and Mr. Townsend, as to create a natural surprise that it had not excited more of the public attention.