This time is different are the four most dangerous words any economist or money manager can utter. We learn new things and invent new technologies. Players come and go. But in the big picture, this time is usually not fundamentally different, because fallible humans are still in charge. (Ken Rogoff and Carmen Reinhart wrote an important book called This Time Is Different on the 260-odd times that governments have defaulted on their debts; and on each occasion, up until the moment of collapse, investors kept telling themselves "This time is different." It never was.)

Nevertheless, I uttered those four words in last week's letter. I stand by them, too. In the next 20 years, we're going to see changes that humanity has never seen before, and in some cases never even imagined, and we're going to have to change. I truly believe this. We have unleashed economic and technological forces we can observe but not entirely control.

I will defend this bold claim at greater length in my forthcoming book, The Age of Transformation.