Leadership is undefined in many dictionaries. Though many suitable definitions exist in books studying leadership, a more appropriate definition can be formed from the parts of the word "leadership." The root word in leadership is lead, which is defined as "to guide by influence." The suffix in the word leadership is –ship, meaning "skill as." In turn, skill is defined as "an art or craft; or ability in such an art or craft." One could thus reason that leadership would then be defined as "the art or craft of influence." Taken one step further, this line of reasoning would logically assume that those who partake in the "art of influence" would then be leaders.

However, not all people believe in this concept of a leader. Leadership implies that one person can make a difference and that the greatest among leaders can and have left their personal stamp on history, whether for good purposes or bad. Some deny this to be true, and instead believe in the theory of historical determinism.

Briefly, historical determinism states that individuals cannot and do not make a difference in the course of history. This theory suggests that history determines the course of the future so completely that anything that happens is merely a reincarnation of the history that has gone before. Followers of this idea believe that leaders are merely labels to distinguish between the separate reincarnations of events, that they are in reality nothing more than "slaves to history."

Leadership, however, clearly refutes this idea. Determinism denies some of the deepest truths of mankind, in particular those of human freedom and responsibility. How can humans be free if they are nothing more than slaves to history? How can any person take responsibility, when their actions are predetermined by history? After all, no person can be fairly rewarded or punished for actions that are outside their control.

History itself further denies any truth to this idea. History had to have been made at one point. If the theory of historical determinism were true, how could history be made where no history existed to provide a basis? The answer is that it could not, and thus we are left with the conclusion that leaders made history. Though undoubtedly history influences leaders, it also assuredly does not rule them.

Thus, the proof of leadership exists in the power of the individual to change the course of history. Based on this proof, leadership is one of the single most powerful tools, if not the most powerful tool, in the history of the world. After all, what other tool exists has altered the very course of history?