More than once during the global financial crisis, the words of John Maynard Keynes have framed our dilemmas. He once said: “The long run is a misleading guide to current affairs. In the long run we are all dead.” He is also held to have said: “The market can stay irrational longer than you can stay solvent.”

Neither of these famous quotations comes from the economist’s published work. But they are widely attributed to Keynes and they represent important truths for investors.