Henderson's Ten Pillars of Economic Wisdom

found here:

1. TANSTAAFL: There ain't no such thing as a free lunch.
2. Incentives matter.
3. Economic thinking is thinking on the margin.
4. The only way to create wealth is to move it from a lower valued to a higher valued use. Corollary: Both sides gain from exchange.
5. Information is valuable and costly.
6. Every action has unintended consequences.
7. The value of a good or service is subjective.
8. Costs are a bad, not a good.
9. The only way to increase a nation's real income is to increase its real output.
10. Competition is a hardy weed, not a delicate flower.