If you're going to buy something which compounds for 30 years at 15% per annum and you pay one 35% tax at the very end, the way that works out is that after taxes, you keep 13.3% per annum. In contrast, if you bought the same investment, but had to pay taxes every year of 35% out of the 15% that you earned, then your return would be 15% minus 35% of 15%-or only 9.75% per year compounded. So the difference there is over 3.5%. And what 3.5% does to the numbers over long holding periods like 30 years is truly eye-opening.

Of course you want to drive that out of yourself because you want to be wise, not foolish. You also have to allow for the self-serving bias of everybody else because most people are not going to remove it all that successfully, the human condition being what it is. If you don't allow for self-serving bias in your conduct, again you're a fool.

Darwin paid particular attention to disconfirming evidence. Objectivity maintenance routines are totally required in life if you're going to be a great thinker.

...in terms of business mistakes that I've seen over a long lifetime, I would say that trying to minimize taxes too much is one of the great standard causes of really dumb mistakes. I see terrible mistakes from people being overly motivated by tax considerations. Warren and I personally don't drill oil wells. We pay our taxes. And we've done pretty well, so far. Anytime somebody offers you a tax shelter from here on in life, my advice would be don't buy it.

We tend to buy things - a lot of things - where we don't know exactly what will happen, but the outcome will be decent.

You need a different checklist and different mental models for different companies. I can never make it easy by saying, 'Here are three things.' You have to derive it yourself to ingrain it in your head for the rest of your life.

I bet Richard Fuld doesn't have an ounce of contrition. It's just megalomania. When it's like that, you need rules to prevent catastrophe. When banks are borrowing the government's credit rating, you need rules to prevent stupid things.