M. Tarde perceived that imitation, as a social form, is only one mode of a universal activity, of that endless repetition, through­out nature, which in the physical realm we know as the undulations of ether, the vibra­tions of material bodies, the swing of the planets in their orbits, the alter­nations of light and darkness, and of seasons, the suc­cession of life and death. Here, then, was not only a fundamental truth of social science, but also a first principle of cosmic philosophy.