"Ideas, the great principles of world renewal, do not advance by their own means. They have no legs, said one of the classics of our thought. They advance and impose themselves when, having penetrated the minds of men and the consciousness of a class, they become a force, because the best among men, and first of all in this class, go into battle for them, face danger, sacrifice their freedom and their lives. (chap. VII, p. 69)"