The idea of evolution by natural
selection and struggle for survival took shape in Darwin’s mind after reading Malthus’
works. Darwin described Malthus’ theory of natural selection in the following
way: “As more individuals are produced than can possibly survive, there must in
every case be a struggle for existence, either one individual with another of
the same species, or with the individuals of distinct species, or with the
physical conditions of life. It is the doctrine of Malthus applied with
manifold force to the whole animal and vegetable kingdoms.”
The Vital Needs Theory - page 75