I found this on JoeCit
Some excerpts ...
When Buffett claims to understand something, he means he understands it almost 100% and can say with virtual certainty what the company will look like in ten or twenty years. It’s not that Buffett is out of touch and doesn’t know what a computer or a prescription drug is. He may have you think that in jest, but, as Bill Gates has said, he knows their businesses, opportunities, and challenges quite well. Yet, and here’s the key, he does not have any advantage or insight into how the will perform in ten years due to the fickleness of their industries.
I personally believe Munger’s influence at Berkshire and on Buffett’s thinking goes, regrettably, unsung. Very unsung. If Munger hadn’t been around, Buffett arguably would not have gained an appreciation of buying great businesses rather than cigar butts. Munger helped make Berkshire’s returns phenomenal, while allowing for scalability that could not have otherwise been achieved. In other words, Berkshire could never have been scaled to its huge size by purchasing cigar butts — there aren’t enough of them, and the returns are not “continuing” (i.e. when they reach fair value, there’s no further upside. You must sell it and move on). Berkshire, therefore, needed to invest in great businesses that it could hold on to.
There is more but the article is best read from the original source (link).
Above passages were copy-pasted from JoeCit.