famous essay on Population[1] the idea that, inasmuch as the struggle for food and other necessities of life was just as pressing among all other organisms as among man, there was a ready explanation of the means by which a purely natural selection could be carried on age after age, without the slightest necessity for guidance by some superior intellect. Under such conditions it would be only natural that the favorable variations would tend to be preserved, while the unfavorable ones were destroyed. The result of this would be the formation of new species. "Here then," says Darwin, "I had at last got a theory by which to work; but I was so anxious to avoid prejudice, that I determined not for some time to write even the briefest sketch of it. In June, 1842, I first allowed myself the satisfaction
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Thomas R. Malthus was an English clergyman who wrote on subjects of political economy. His most famous work, and the one which so aided Darwin is titled, Essay on the Principles of Population as it Affects the Future Improvement of Society, and was published in 1798. Malthus believed that "population unchecked goes on doubling itself every twenty-five years—or increases in geometrical ratio. The rate according to which the productions of the earth increase must be totally of a different nature from the ratio of the increase of population. … The power of propagation being in every period so much superior (to that of production), the increase of the human species can only be kept down to the level of the means of subsistence by the constant operation of the strong law of necessity, acting as a check on the greater power.”
It is easy to see how this exposition applied to the problem on which Darwin was working, and the assistance it must have given him.
