London, T. Bensley for J. Johnson, 1806. . Third edition, 2 vols, 8vo, xvi, 501, [63]; vii, 559 pp., contemporary tree calf gilt, red morocco labels, some pale foxing, a very good set. The first two-volume edition. Contains important additions and corrections to the earlier editions, including replies to his critics.'The central idea of the essay -- and the hub of Malthusian theory -- was a simple one. The population of a community, Malthus, suggested, increases geometrically, while food supplies increased only arithmetically. If the natural increase in population occurs, the food supply becomes insufficient and the size of the population is checked by 'misery' -- that is, the poorest sections of the community suffer disease and famine. The Essay was highly influential in the progress of thought in early nineteenth-century Europe' (PMM).'His work was an important influence on both Darwin and Wallace in their formulation of the concept of natural selection. It also had a profound…