I was really interested in 20th century communalism and alternative communities, the boom of communes in the 60s and 70s. That led me back to the 19th century. I was shocked to find what I would describe as far more utopian ideas in the 19th century than in the 20th century. Not only were the ideas so extreme, but surprising people were adopting them.

The Jacksonian era is generally talked about in terms of individualism, and the development of free market capitalism, and Victorian prudery. It was shocking to find a parallel history to that - a bunch of Americans with very different priorities. I stumbled on to these people, and then became completely fixated on them. The question that drove me was: how did these reasonable people adopt these extremely unreasonable ideas?

That to me was one of the most exciting, and weird puzzles of this book: how are the most religious people and the least religious people of their time all drawn to very similar visions of utopia?

Because the utopian's worldview was framed around moving toward this perfected future, it helped stimulate the private exertions that add up to social progress. Progress is work. People need to build things and sacrifice and have a harder life for things to get better. On its own, I don't think even the most brilliant critique stimulates that kind of effort as well as an appealing vision of the future.

There are two instances I studied in which a community moved, amazingly, into an preexisting village built by other, earlier communalists. The Rappites were a German millenarian sect I mostly leave out of the story, even though they are fascinating, because they're focused on salvation and retreating from the world, as opposed to transforming it, like the other groups I write about.

They're people who probably imagine that they would have had a better time in the past. I wouldn't imagine you'd encounter a lot of black people saying 'Oh, the '50s, that was when America was great.' It's very dangerous because the past was imperfect, and you can't go back anyway.

But if you'd only ever lived in small wooden house in the middle of wilderness, it sounded much better. Especially because it provided intense community, and these people lived in incredible isolation.