There is a difference between leadership and management. The leader and the men who follow him represent one of the oldest, most natural, and most effective of all human relationships. The manager and those he manages are a later product with neither so romantic, nor so inspiring a history. Leadership is of the spirit, compounded of personality and vision – its practice is an art. Management is of the mind, more a matter of accurate calculation, statistics, methods, timetables, and routine – its practice is a science. Managers are necessary; leaders are essential.