The Fog of War entry on Wikipedia

The film's eleven lessons

1. Empathize with your enemy.
2. Rationality will not save us.
3. There's something beyond one's self.
4. Maximize efficiency.
5. Proportionality should be a guideline in war.
6. Get the data.
7. Belief and seeing are both often wrong.
8. Be prepared to reexamine your reasoning.
9. In order to do good, you may have to engage in evil.
10. Never say never.
11. You can't change human nature.