Where's the activism? Nobody knows. And anyone who thinks they know, like Todd Gitlin, has their head up their ass. Nobody knows. The day before every revolution that's ever happened, that revolution was impossible. The day before Rosa Parks, that was impossible. The day after, it was inevitable.

There were no political ideas. It was an apolitical time. It was the '50s and in the privilege of the suburbs.

We were very excited and we brought speakers in – then it so happened that there was a marine recruiter in the center of campus and one of our brothers, one SDS person put up a sign with a quote from the Nuremberg trial and an arrow point at the marine recruiter, saying, "This man is a war criminal." My younger brother and I, he was freshman and I was a sophomore, got caught up in the debates that were swirling around the center of campus and the young Trotskyists had put out a fact sheet on Vietnam that was phenomenal.

Chicago '68 was a relatively small demonstration for its time, but I've talked to millions of people who claim they were there because it felt like we were all there. Everyone from our generation was there and was at Woodstock.

Every politician - FDR, Lyndon Johnson, Abraham Lincoln, Barack Obama - they're all conservative by nature. They are part of the big thing and they're moving in a very constrained world.

My brother and I met several times during that weekend trying to figure out what we were each going to do, and we met for breakfast the morning of the sit-in and I had decided that I was going to go get arrested, and he decided that he was going to have the harder job and go tell our parents that I'd been arrested.

Part of the fun of writing, touring, teaching, is engaging with real people about all of it: what to do now, how to build a movement, of approaches to teaching, of parenting - it's exciting to be in that dialogue.