Points well taken Perry.  You just reinforced my belief that leadership isn't something to be defined, but rather a context to think from in choosing our actions.  The leaders we study did great things.  If our study of leadership does not directly influence the choices we make and the actions we take then why bother?  To influence our actions it must first influence our thinking.  As David points out the study of leadership can help us "stand on the shoulder of giants".

Yet even if the people we have identified in history as great leaders did not study leadership the ways we do today I would imagine there was someone they aspired to be like and/or people they learned from along the way in accomplishing the extraordinary.  They may not have focused on a subject called leadership but they likely learned and grew as leaders by studying and being advised by others so they could accomplish what they set out to accomplish.