Here is the idea at the center of it. Money has come in two families for about as long as we have had money. There is value that travels by possession: the coin, the note, the bill in your pocket that asks nothing of anyone. And there is value that travels by permission: the tally, the ledger, the account entry that moves only when a chain of institutions agrees to move it. Neither family is wicked. A healthy monetary world has always kept both, because each covers the other's failures. The story of our moment is that the first family is being retired, and the second family is being wired to a switch.