I was having a conversation with a real estate professional who’s interested in New Urbanism, and generally in doing better than suburban sprawl. (A lot of them are, by the way, and that doesn’t mean we’re all “developer shills.” In addition, I guess, to being both communists and market fundamentalists.)

I had an interesting thought. These different strains of urbanism, broadly understood—the tradition-minded New Urbanists, the technocratic Smart Growthers, the libertarian-ish YIMBYs—are, obviously, putting forward a vision or framework for how they think development should proceed today. But they are also, in some ways, trying to describe or figure out how development used to work—or, more precisely, trying to reverse engineer, in modern conditions, whatever might be the Platonic-form equivalent of America’s old urbanism...