Thomas Robert Malthus was born near Dorking, Surrey, England, Feb. 17, 1766, and after passing through the University of Cambridge was ordained, and travelled on the Continent. His great work, "An Essay on the Principle of Population as it Affects the Future Improvement of Society," was first published Anonymously in 1798, and five years later it appeared, under the title of "An Essay on the Principle of Population, or a View of its Past and Present Effect on Human Happiness, with an Enquiry into our Prospects Respecting the Future Removal or Mitigation of the Evils which it Occasions," under the author's name. Malthus is one of the most persistently misrepresented of great thinkers, his central doctrine being nothing less moral than that young men should postpone marriage until they have the means of supporting a family. It is of the first interest in the history of thought that the reading of this great essay of Malthus should have independently suggested, first to Charles Darwin, and later to Alfred Russel Wallace, the idea of natural selection as a necessary consequence of that struggle for life so splendidly demonstrated by Malthus in the case of mankind. It is to be wondered that Malthus, having provided himself with the key to the great problem of organic evolution, should have left its use to others. One explanation is, doubtless, that his survey was not comparative, covering the whole range of life, but was practically confined to one living form. Malthus died on December 23, 1834. _I.--General Survey of the Checks to Population_ Since population is capable of doubling itself at least once in every twenty-five years, and since the supply of food can increase in only arithmetical ratio, it follows that increase of population must always be checked by lack of food. But, except in cases of famine, this check is never operative, and the chief checks to increase of population are moral restraint, vice, and misery. In spite of these checks, which are always more or less in operation, there is a constant tendency for the population to increase beyond the means of subsistence. Such increase is followed by lowered wages, dearer food, and thus a lowered marriage-rate and birth-rate; and the lowered wages, in turn, induce more agricultural enterprise, and thus means of subsistence become more abundant again. More abundant and cheaper food, in turn, promotes marriage, and increases the population, until again there is a shortage of food; and this oscillation, though irregular, will always be found, and there will always be a tendency for the population to oscillate around the food limit.