But I continued to think that illness happened to patients and not to doctors, even though I was now retired. Twenty months after I had my brain scanned, I was diagnosed with advanced prostate cancer. I had had typical symptoms for years, steadily getting worse, but it took me a long time before I could bring myself to ask for help. I thought I was being stoical when in reality I was being a coward.

In 1990 I retired from my firm, I.M. Pei & Partners, and for two years I didn't do much. Then I started to get kind of antsy, so I decided, I'm going to do some more work. And I chose to do work outside the U.S. because I've spent 45 years here and I wanted to learn more about what's happening in the rest of the world.

Now, it's been very hard for me to accept that. I never - I felt like - I always felt like I could blow it and nothing would never happen until this happened. So now, it's - no matter how hard I practice, it just seem like I can't do the plays I did.

There are things that I really am interested in doing that I can't do if I continue to do what I'm doing. And I - teaching would be a big thing for me. I'm an adjunct instructor at Johns Hopkins and teach business communications and ethics, so very different from what I do on a daily basis.

We've just passed a milestone: Twenty years ago, on January 3, 1972, Blue Chip Stamps (then an affiliate of Berkshire and later merged into it) bought control of See's Candy Shops, a West Coast manufacturer and retailer of boxed-chocolates. The nominal price that the sellers were asking - calculated on the 100% ownership we ultimately attained - was $40 million. But the company had $10 million of excess cash, and therefore the true offering price was $30 million. Charlie and I, not yet fully appreciative of the value of an economic franchise, looked at the company's mere $7 million of tangible net worth and said $25 million was as high as we would go (and we meant it). Fortunately, the sellers accepted our offer. The sales of trading stamps by Blue Chip thereafter declined from $102.5 million in 1972 to $1.2 million in 1991. But See's candy sales in the same period increased from $29 million to $196 million. Moreover, profits at See's grew even faster than sales, from $4.2 million pre-tax in 1972 to $42.4 million last year.

My first mistake, of course, was in buying control of Berkshire. Though I knew its business - textile manufacturing - to be unpromising, I was enticed to buy because the price looked cheap. Stock purchases of that kind had proved reasonably rewarding in my early years, though by the time Berkshire came along in 1965 I was becoming aware that the strategy was not ideal. If you buy a stock at a sufficiently low price, there will usually be some hiccup in the fortunes of the business that gives you a chance to unload at a decent profit, even though the long-term performance of the business may be terrible. I call this the "cigar butt" approach to investing. A cigar butt found on the street that has only one puff left in it may not offer much of a smoke, but the "bargain purchase" will make that puff all profit. Unless you are a liquidator, that kind of approach to buying businesses is foolish.

I go in every day to the office. I don't accomplish hardly anything. I mean, in terms of – it just takes me way longer to do things. And Greg is so good. It was kind of embarrassing how good he is, because he has covered – you know, we've got about 200 businesses within Berkshire, you know, that came about, and I can't name the manager's names or their wives names, or – and I haven't seen them, you know, in a long time. It's easier just to write the letter once a year and kind of do my own thing. Greg covers more ground in a day than I would in a week, even when I was at my peak, let alone my present condition.

And now, you've got nine countries, including, you know, a guy in North Korea. I mean, and there will be, something will happen. And we worried enormously about it when there were two. And we had perfectly, we had really pretty sane leaders in Kennedy and Khrushchev. You know, I mean, you were not dealing with unstable people or anything like that.

The extraordinary delegation of authority now existing at Berkshire is the ideal antidote to bureaucracy. In an operating sense, Berkshire is not a giant company but rather a collection of large companies. At headquarters, we have never had a committee nor have we ever required our subsidiaries to submit budgets (though many use them as an important internal tool). We don't have a legal office nor departments that other companies take for granted: human relations, public relations, investor relations, strategy, acquisitions, you name it. We do, of course, have an active audit function; no sense being a damned fool.

The reaction of my family and me to our extraordinary good fortune is not guilt, but rather gratitude. Were we to use more than 1% of my claim checks on ourselves, neither our happiness nor our well-being would be enhanced. In contrast, that remaining 99% can have a huge effect on the health and welfare of others.