One of the reasons I can have a concentrated portfolio is because I understand what I own…. If you own six or eight great things, or at least great bets, that’s more comforting if you actually know what you own. If you don’t know what you own, if you don’t know how to value a business, you’re just going to react to the emotions, because you don’t actually understand what you own. But if you actually understand what you own, and the premise that you bought those things with is still intact, that’s actually the only way I think you can deal with the emotion, because you realize what you own is still good

—Joel Greenblatt