The Victorian Age was the culmination of changes in the political, social, scientific, theological and cultural spheres throughout Europe. Darwin's newly elaborated evolutionary idea was the pivot for social Darwinism, a theory based on the gradual movement of the species toward greater self-awareness and strength. Shaw described this process in his play Man and Superman. Freud also utilized the concept in his libido theory. Horney interpreted the process as a psychic response to the intense societal pressures to succeed. A linkage of interdependence and progression of these ideas emerges as the world continues to evolve.