Level 5 leaders are fanatically driven, infected with an incurable need to produce sustained results. They are resolved to do whatever it takes to make the company great, no matter how big or hard the decisions.

That good is the enemy of great is not just a business problem. It is a human problem.

I am completely Socratic.

For no matter what we achieve, if we don't spend the vast majority of our time with people we love and respect, we cannot possibly have a great life. But if we spend the vast majority of our time with people we love and respect - people we really enjoy being on the bus with and who will never disappoint us - then we will almost certainly have a great life, no matter where the bus goes. The people we interviewed from the good-to-great companies clearly loved what they did, largely because they loved who they did it with.

The only way to deliver to the people who are achieving is to not burden them with the people who are not achieving.

The best CEOs in our research display tremendous ambition for their company combined with the stoic will to do whatever it takes, no matter how brutal (within the bounds of the company's core values), to make the company great. Yet at the same time they display a remarkable humility about themselves, ascribing much of their own success to luck, discipline and preparation rather than personal genius.

Level 5 leaders channel their ego needs away from themselves and into the larger goal of building a great company. It's not that Level 5 leaders have no ego or self-interest. Indeed, they are incredibly ambitious-but their ambition is first and foremost for the institution, not themselves.