The thought was, 'We're going to go to California, where the soil is black and ten feet deep, and there are no rocks, and there's gold in the hills.' The West becomes the surface onto which people project their fantasies, where once the future had been the place they projected their fantasies. So it's not just the war that ends the utopian communities, but what follows.

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?

They [Oneida people] didn't want to fix problems one at a time. If someone invited them to a feminist convention, their answer would have been, 'In the new world women will have total equality, so lets spend our energy creating that whole new world.' And to their credit, the women at Oneida probably had far greater practical equality than what any of the women gathered at Seneca Falls experienced in their lifetimes.

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.

The thing that had fueled these utopian communities was a literal belief, and not just a general sense of optimism, that the earth was about to become a paradise. That idea cannot hold water after the war.

The Enlightenment faith that things are getting a little bit better each decade becomes difficult to support. People recognized that there had just been a war that was worse than the war of 1812, and worse than the Revolution; things were clearly not getting better and better.

The secular utopians basically said the exact same thing, they just took the Bible out of the equation. The religious and the secular groups recognized each other as fellow travellers. They exchanged newsletters and asked each other questions like, "What's a good soup pot to use if you're making dinner for 800 people?" They had these practical connections.