The stronger must dominate and not mate with the weaker, which would signify the sacrifice of its own higher nature. Only the born weakling can look upon this principle as cruel, and if he does so it is merely because he is of a feebler nature and narrower mind, for if such a law did not direct the process of evolution then the higher development of organic life would not be conceivable at all. Adolph Hitler, Mein Kampf