It is chiefly the psychologists of the school of Freud who have pointed out that many of man's thoughts and actions are compensatory substitutes for desires which he has been obliged to suppress. A thing may be desired not for its intrinsic worth or usefulness, but because he has unconsciously come to see in it a symbol of something else, the desire for which he is ashamed to admit to himself...This general principle, that men are very largely actuated by motives which they conceal from themselves, is as true of mass as of individual psychology...Human desires are the steam which makes the soial machine work. Only by understanding them can the propagandist control that cast, loose-jointed mechanism which is modern society.