My Capital Writing interview with Jennifer Burns, the author of a new biography about Milton Friedman, is up now.

I misspoke (at least) twice during the interview. The first was when I said Friedman was willing to “smash sacred cows,” completely mangling that idiom. It hurt my ears listening to it, but there it is on the internet forever.

The second was when I talked about a famous put-down of Friedman. An economist mocked Friedman’s monetarism by saying, “Everything reminds Milton of the money supply. Well, everything reminds me of sex, but I keep it out of the paper.” I couldn’t remember in the moment whether it was Robert Barro or Robert Solow. As Burns said, it was Solow.

News of Solow’s death at the age of 99 broke yesterday. I wrote a post this morning about his greatest contribution to economics, the exogenous growth model, and a few of its implications. But that quote about Friedman is another contribution that will last.

Part of the reason is probably that sex sells, and there isn’t much sex in economics. It is genuinely witty, so that helps. It’s one of the only times Friedman was on the receiving end of someone else’s wit, as he was quite witty himself. And Friedman could be monomaniacal about the money supply, so it’s not an entirely unfair joke.

Also, some aspects of Friedman’s monetarism turned out to be wrong. As Burns records in the book, Friedman thought inflation would return in the mid 1980s after the Volcker shock, but it did not. Some of the historical relationships between the money supply and other metrics did not hold into the future.

It is important to keep in mind that nobody has macroeconomics all figured out. Friedman’s contribution for monetary policy was to remind economists that money matters. Believe it or not, that was a controversial take at the time, but it is commonly accepted now. Exactly what that means varies, but good economists have to at least think about money in relation to business cycles now, largely because of Friedman. His obsession wasn’t for nothing.