Borrowing some notorious investor words, it’s always different this time around, but it’s never really all that different. We say that because there is some evidence that we might be in a rare period of rational exuberance—where sentiment across the financial industry seems to be broadly positive, outside of the usual critical and cynical stalwarts—but it’s kind of a cautious positivity. History has taught us that such a period, if we are really in one, should not last very long.