Special Section: Who Were History's Great Leaders?

What makes a great leader?

Throughout history, who qualifies? TIME asked a variety of historians, writers, military men, businessmen and others for their selections.

MORTIMER ADLER, U.S. philosopher: In Aristotelian terms, the good leader must have ethos, pathos and logos. The ethos is his moral character, the source of his ability to persuade. The pathos is his ability to touch feelings, to move people emotionally. The logos is his ability to give solid reasons for an action, to move people intellectually. By this definition, Pericles of Athens was a great leader.

Winston Churchill, Thomas Jefferson,...