In some respects this influence has been harmful to both ethical theory and practice. In the domain of philosophy it may best be traced in the teachings of Nietzsche. Nietzsche insists that man must follow the lead of nature; that the struggle for existence must be kept up on the human plane just as it goes on in the lower realms of life; that the strong should use for their own advancement the weak; that the nurture and care of the defective and weak is a crime against humanity[734]--for “the hope of the future lies in perfecting the strong, not in strengthening the weak”; that only through the struggle for existence has nature produced her highest type, man, and that it is only through obedience to this great cosmic law, in accordance with which the higher prey upon the lower, that “the superman,” the highest possible type of mankind, can be brought into existence. This teaching tends to steel the heart against human sympathy and to blunt all the finer sensibilities. It seems to justify and excuse all kinds of antisocial action. And, indeed, the doctrine has been used as a justification and excuse not only of individual self-assertion and egotism but of national and race self-assertion and egotism as well. Modern imperialism has sought to justify aggression upon weaker and so-called “inferior races” by an appeal to this law of evolution as it works on the lower levels of life. Thus the doctrine has in a certain measure fostered national egotism, and has stood right in the way of the development of a true international morality. [Sidenote: Altruism _versus_ egotism in the cosmic process] But these drifts toward egotism in modern philosophy and life induced by evolutionary science are more than compensated by opposing movements of ethical thought created by a truer interpretation of the facts of evolution and a deeper insight into the cosmic process.[735]