What is leadership? Not only has that question been debated since the beginning of human culture and society, but it's a moving target based on the definer, and the epoch. The definition can be thought-provoking and profound: A leader is best when people barely know he exists, not so good when people obey and acclaim him, worse when they despise him, (Lao Tzu, 6th century BC ). Or the profundity may lie shrouded in the prosaic: A leader is one who has followers, (Peter Drucker, 20th century). However you define the concept, today's challenges for leaders of all stripes are monumental, and the need for effective leadership is huge. More than anything, this set travels farther and digs deeper than most leadership books. It takes us from mere explanations of leadership to an understanding of it as part of the human condition. Reading it should be at the top of the to-do list for any leader in any era.