You must know the big ideas in the big disciplines, and use them routinely - all of them, not just a few. Most people are trained in one model - economics, for example - and try to solve all problems in one way. You know the old saying: to the man with a hammer, the world looks like a nail. This is a dumb way of handling problems.

I think it is undeniably true that the human brain must work in models. The trick is to have your brain work better than the other person's brain because it understands the most fundamental models- ones that will do most work per unit.

Look at those hedge funds - you think they can wait? They don't know how to wait! I have sat for years at a time with $10 to $12 million in treasuries or municipals, just waiting, waiting...As Jesse Livermore said, 'The big money is not in the buying and selling...but in the waiting.'

[With] closet indexing....you're paying a manager a fortune and he has 85% of his assets invested parallel to the indexes. If you have such a system, you're being played for a sucker.

If you're going to be an investor, you're going to make some investments where you don't have all the experience you need. But if you keep trying to get a little better over time, you'll start to make investments that are virtually certain to have a good outcome. The keys are discipline, hard work, and practice. It's like playing golf - you have to work on it.

Don't confuse correlation and causation. Almost all great records eventually dwindle.

Of course I'm troubled by huge consumer debt levels - we've pushed consumer credit very hard in the US. Eventually, if it keeps growing, it will stop growing. As Herb Stein said, "If something cannot go on forever, it will stop." When it stops, it may be unpleasant. Other than Herb Stein's quote, I have no comment. But the things that trouble you are troubling me.