Problem of Malthus stated

Darwin(page 52, Origin of Species) has observed *' that in a state of nature almost every full-grown plant annually produces seed, and amongst animals there are few which do not annually pair. Hence we may confidently assert that all plants and animals are tending to increase at a geometrical ratio—that all would rapidly stock every station in which they could anyhow exist. And this geometrical tendency to increase must be checked by destruction at some period of life," and, as an inevitable consequence, he goes on to add " that each individual lives by a struggle at some period of its life, that heavy destruction falls either on the young or old during each generation, or at recurrent intervals.
Lighten any check, mitigate the destruction ever so little, and the number of the species will almost instantaneously increase to any amount." These considerations when fully appreciated form the foundation of the problem of Malthus. - An Essay on the Principle of Population. Malthus, (2 vols. Loudon, 1826.)