Long ago, Sir Isaac Newton gave us three laws of motion, which were the work of genius. But Sir Isaac's talents didn't extend to investing: He lost a bundle in the South Sea Bubble, explaining later, 'I can calculate the movement of the stars, but not the madness of men.' If he had not been traumatized by this loss, Sir Isaac might well have gone on to discover the Fourth Law of Motion: For investors as a whole, returns decrease as motion increases.

The line separating investment and speculation, which is never bright and clear, becomes blurred still further when most market participants have recently enjoyed triumphs. Nothing sedates rationality like large doses of effortless money. After a heady experience of that kind, normally sensible people drift into behavior akin to that of Cinderella at the ball. They know that overstaying the festivities -- that is, continuing to speculate in companies that have gigantic valuations relative to the cash they are likely to generate in the future -- will eventually bring on pumpkins and mice. But they nevertheless hate to miss a single minute of what is one helluva party. Therefore, the giddy participants all plan to leave just seconds before midnight. There’s a problem, though: They are dancing in a room in which the clocks have no hands.

It's class warfare, my class is winning, but they shouldn't be. May 25 2005, in arguing the need to raise taxes on the rich.

The managers at fault periodically report on the lesson they have learned from the latest disappointment. They then usually seek out future lessons.

The speed at which a business success is recognized, furthermore, is not that important as long as the company's intrinsic value is increasing at a satisfactory rate. In fact, delayed recognition can be an advantage: It may give us the chance to buy more of a good thing at a bargain price.

I’d be a bum on the street with a tin cup if the markets were always efficient.

The strategy we've adopted precludes our following standard diversification dogma. Many pundits would therefore say the strategy must be riskier than that employed by more conventional investors. We disagree. We believe that a policy of portfolio concentration may well decrease risk if it raises, as it should, both the intensity with which an investor thinks about a business and the comfort-level he must feel with its economic characteristics before buying into it.

In a bull market, one must avoid the error of the preening duck that quacks boastfully after a torrential rainstorm, thinking that its paddling skills have caused it to rise in the world. A right-thinking duck would instead compare its position after the downpour to that of the other ducks on the pond. Letter to Berkshire Hathaway shareholders, 1997.

Like an oversexed guy in a whorehouse. Now is the time to invest and get rich. Answering to the question: "How do you feel?", in an interview with Forbes in October 1974.

Those who attended (the annual meeting) last year saw your Chairman pitch to Ernie Banks. This encounter proved to be the titanic duel that the sports world had long awaited. After the first few pitches...I fired a brushback at Ernie just to let him know who was in command. Ernie charged the mound, and I charged the plate. But a clash was avoided because we became exhausted before reaching each other.

Berkshire’s arbitrage activities differ from those of many arbitrageurs. First, we participate in only a few, and usually very large, transactions each year. Most practitioners buy into a great many deals perhaps 50 or more per year. With that many irons in the fire, they must spend most of their time monitoring both the progress of deals and the market movements of the related stocks. This is not how Charlie nor I wish to spend our lives. (What’s the sense in getting rich just to stare at a ticker tape all day?)

If I was running $1 million today, or $10 million for that matter, I'd be fully invested. Anyone who says that size does not hurt investment performance is selling. The highest rates of return I've ever achieved were in the 1950s. I killed the Dow. You ought to see the numbers. But I was investing peanuts then. It's a huge structural advantage not to have a lot of money. I think I could make you 50% a year on $1 million. No, I know I could. I guarantee that.

The approach and strategies are very similar in that you gather all the information you can and then keep adding to that base of information as things develop. You do whatever the probabilities indicated based on the knowledge that you have at that time, but you are always willing to modify your behaviour or your approach as you get new information. In bridge, you behave in a way that gets the best from your partner. And in business, you behave in the way that gets the best from your managers and your employees.

I wouldn’t mind going to jail if I had three cellmates who played bridge.

I just don't see anything available that gives any reasonable hope of delivering such a good year and I have no desire to grope around, hoping to 'get lucky' with other people's money. I am not attuned to this market environment, and I don't want to spoil a decent record by trying to play a game I don't understand just so I can go out a hero.

When a management with a reputation for brilliance tackles a business with a reputation for bad economics, it is usually the reputation of the business that remains intact.

We have tried occasionally to buy toads at bargain prices with results that have been chronicled in past reports. Clearly our kisses fell flat. We have done well with a couple of princes - but they were princes when purchased. At least our kisses didn't turn them into toads. And, finally, we have occasionally been quite successful in purchasing fractional interests in easily-identifiable princes at toad-like prices. 1981 Chairman's Letters to Shareholders.

I am out of step with present conditions. When the game is no longer played your way, it is only human to say the new approach is all wrong, bound to lead to trouble, and so on. On one point, however, I am clear. I will not abandon a previous approach whose logic I understand ( although I find it difficult to apply ) even though it may mean foregoing large, and apparently easy, profits to embrace an approach which I don't fully understand, have not practiced successfully, and which possibly could lead to substantial permanent loss of capital. In a letter to his partners in the stock market frenzy of 1969.

First, many in Wall Street - a community in which quality control is not prized - will sell investors anything they will buy.

Our future rates of gain will fall far short of those achieved in the past. Berkshire's capital base is now simply too large to allow us to earn truly outsized returns. If you believe otherwise, you should consider a career in sales but avoid one in mathematics (bearing in mind that there are really only three kinds of people in the world: those who can count and those who can't). 1998 Chairman's Letter to Shareholders.