I found a comment from George Schultz (recent interview with Charlie Rose – see video) particularly interesting:
Sometimes change happens simply because the leader thinks it can happen.
He was referring to the fall of the Berlin Wall 20 years ago and the impact of Reagan’s optimism and Gorbachev’s open-mindedness.  I often wonder if optimism is a [...]

The challenge to all of us who work with executives is that maybe they don’t matter so much.  Studies show the effect of CEOs on firm performance to range from 4.5-12.8%.  It’s as Napoleon said, “Luck is the most essential ingredient of good generalship.”
Read more:  http://www.theatlantic.com/doc/200906/steve-jobs