Patience and discipline can make you look foolishly out of touch until they make you look prudent and even prescient

Speculators are obsessed with predicting: guessing the direction of stock prices. Every morning on cable television, every afternoon on the stock market report, every weekend in Barron's, every week in dozens of market newsletters, and whenever business people get together. In reality, no one knows what the market will do; trying to predict it is a waste of time, and investing based upon that prediction is a purely speculative undertaking.

The cost of performing well in bad times can be relative underperformance in good times.

Selling, in particular, can be a challenge; many investors are tempted to become more optimistic when a security is performing well. This temptation must be resisted; tax considerations aside, when a security reaches full valuation, there is no longer a reason to own it.

Depressions aren't good but the depression mentality is good.

Excess capacity in people, machines, or property will be quickly absorbed.

Beware leverage in all its forms. Borrowers - individual, corporate, or government - should always match fund their liabilities against the duration of their assets. Borrowers must always remember that capital markets can be extremely fickle, and that it is never safe to assume a maturing loan can be rolled over. Even if you are unleveraged, the leverage employed by others can drive dramatic price and valuation swings; sudden unavailability of leverage in the economy may trigger an economic downturn.