From Plato to David Petraeus, distinguished writers have tried to uncover the essential principles and behaviors of successful leaders. They have emphasized toughness and sensitivity, thundering eloquence and quiet contemplation, and, most recently, devotion to a True North and “emotional intelligence.” Leadership often appears to be everything and nothing at the same time — a mix of trite advice, contradictory analysis and ponderously obvious observation. Has any successful leader ever used any of the books on leadership?