We will now discuss in a little more detail the struggle
for existence. . . . Nothing is easier than to admit in words the truth of the
universal struggle for life, or more difficult - at least I have found it so -
than constantly to bear this conclusion in mind. Yet unless it be thoroughly
engrained in the mind, I am convinced that the whole economy of nature, with every
fact on distribution, rarity, abundance, extinction, and variation, will be
dimly seen or quite misunderstood.
Charles Darwin, The Origin of the Species
