Buffett should follow his own advice, and stick to commenting on things that he understands.
> In The Theory of Investment Value, written over 50 years ago, John Burr Williams set forth the equation for value, which we condense here: The value of any stock, bond or business today is determined by the cash inflows and outflows - discounted at an appropriate interest rate - that can be expected to occur during the remaining life of the asset.
- Buffett in http://www.berkshirehathaway.com/letters/1992.html