In a state of nature almost every full-grown plant annually produces seed, and among animals there are very 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 any how exist, and that this geometrical tendency to increase must be checked by destruction at some period of life. Our familiarity with the larger domestic animals tends, I think, to mislead us; we see no great destruction falling on them, and we do not keep in mind that thousands are annually slaughtered for food, and that in a state of nature an equal number would have somehow to be disposed of.

The only difference between organisms which annually produce eggs or seeds by