Friedrich Engels was in some ways as important as Marx in helping to establish the revolution called Marxism (Communism) that has changed the world. It was Engels who brought Darwinism into Marx's life and the socialist/communist movement. His role, and the influence of Darwinism, were both important, although Darwinism is a more important part of the radical-left movement today than in the days of Marx. The contribution of both Engels and Marx were intertwined; thus Engels' work cannot be discussed without covering the contribution of his close co-worker, Karl Marx.