“Gods, whether of Progress or the Old Testament, ghosts of saintly, or revolutionary, ancestors, abstracted moral imperatives, ideals cut wholly off from mere earth and mankind, utopias beckoning from the marshes of their never-never-land—these, and not the facts of social life together with probable generalizations based on those facts, exercise the final controls over arguments and conclusions. Political analysis becomes, like other dreams, the expression of human wish or the admission of practical failure.”