In 2009, the historian David Kaiser, then a professor at the Naval War College in Newport, Rhode Island, got a call from a guy named Steve Bannon.

Bannon wanted to interview Kaiser for a documentary he was making based on the work of the generational theorists William Strauss and Neil Howe. Kaiser, an expert on Strauss and Howe, didn’t know Bannon from Adam, but he agreed to participate. He went to the Washington headquarters of the conservative activist group Citizens United, where Bannon was then based, for a chat.

Kaiser was impressed by how much Bannon knew about Strauss and Howe, who argued that American history operates in four-stage cycles that move from major crisis to awakening to major crisis. These crises are called “Fourth Turnings” — and Bannon believed the U.S. had entered one on Sept. 18, 2008, when Hank Paulson and Ben Bernanke went to Capitol Hill to ask for a bailout of the international banking system.