It’s almost a tradition. For generations, Americans eager for insurrection have traveled the world in search of an exemplar to deify. Sometimes what they’ve found has horrified them. Other times it hasn’t — but it should have.

By 1978, American left groups had grown increasingly distant from mass politics yet ever more radical in their aspirations. So it’s hardly a surprise that three years into the death camp revolution that would kill a quarter of the country’s population, an American Marxist could celebrate Cambodia as “a nation reborn, a nation that has regained its soul.”

The man who wrote those words was David Kline, one of the few Americans permitted a visit to the Khmer Rouge’s bloody playground. As a guest of Foreign Minister Ieng Sary, he traveled to Democratic Kampuchea along with three other members of the Communist Party Marxist-Leninist (CP-ML) — a Maoist organization grown out of the October League, which, like so many New Left groups, had itself sprouted from the remains of Students for a Democratic Society.