As the old joke goes, St Peter had some bad news for an oil prospector who appeared at the pearly gates of Heaven: “You’re qualified for admission,” said St Peter. “But, as you can see, the section for oil prospectors is packed. There’s no way to fit you in.” After a moment, the prospector asked to say just four words to the occupants. That seemed harmless to St Peter, so the prospector yelled, “Oil discovered in Hell!” Immediately, most of the prospectors stampeded out for the nether regions. Impressed, St Peter invited the prospector to stay. The prospector paused, saying: “No, I think I’ll go along with the rest of them. There might be some truth to that rumour after all.”

Let that be a warning to CEOs and shareholders. Steering clear of rumours and self-delusion has been one of Warren Buffett’s key rules, ingrained into Berkshire Hathaway shareholders for years. We all need to hear such lessons repeatedly because reality’s temptations are always at war with our ideals.