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

A simple rule applies: if you don't quickly comprehend what a company is doing, then management probably doesn't either.

Why should the immediate opportunity set be the only one considered, when tomorrow's may well be considerably more fertile than today's?

In a rising market, everyone makes money and a value philosophy is unnecessary. But because there is no certain way to predict what the market will do, one must follow a value philosophy at all times.

Investing is the intersection of economics and psychology. The analysis is actually the easy part. The economics, the valuation of the business isn't that hard. The psychology - how much do you buy, do you buy it at this price, do you wait for a lower price, what do you do when it looks like the world might end - those things are harder. Knowing whether you stand there, buy more, or whether something has legitimately gone wrong and you need to sell, those are harder things. That you learn with experience, by having the right psychological makeup.

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.

It is important to remember that value investing is not a perfect science. It is an, with an ongoing need for judgment, refinement, patience, and reflection. It requires endless curiosity, the relentless pursuit of additional information, the raising of questions, and the search for answers. It necessitates dealing with imperfect information - knowing you will never know everything and that that must not prevent you from acting. It requires a precarious balance between conviction, steadfastness in the face of adversity, and doubt - keeping in mind the possibility that you could be wrong.