One of Margaret Thatcher’s more quoted sayings is “The facts of life are conservative.” It’s a remark that covers a great deal of ground, since it applies to entire societies as well as to individuals. In conventional politics it applies most obviously to economic policy. There the facts of life teach that you can’t spend more than you earn, at least in the long run, and that if you borrow to finance an investment that pays less than the interest on your loan, you’ll end up eventually in Carey Street (where the bankruptcy court is located). In work and personal …