Burrough does more, offering lessons to absorb. One involves the inner logic that leads sensitive souls of various ideological predilections to embrace violence for political ends. The number of American leftists studying bomb-making over the last couple of decades may be vanishingly small, but the number of Americans is not: Timothy McVeigh and his drums of fertilizer; the Tsarnaev brothers and their pressure cookers; abortion-clinic bombers; young Minnesotans scouring the Internet for ways to travel to Syria to join ISIS—all of them are seekers of a certain kind of Dostoyevskian fantasy of communion. They are radical narcissists detached from reality, certain that their spark would ignite the great silent masses who share the same sense of futility and frustration. They see society as a powder keg almost ready to blow. The book provides rich raw material to draw these connections, even if Burrough’s own analysis, and his engagement with scholarship about what makes violent extremists tick, is thin. (“What the underground movement was truly about—what it was always about—was the plight of black Americans”: This is his reductive conclusion, when his own evidence points to much more.)

Another lesson is about the counterproductive patterns of thought and action recognizable on the left today, such as the notion that there is no problem with radicalism that can’t be solved by a purer version of radicalism, or that the participant in any argument who can establish him- or herself as the most oppressed is thereby naturally owed intellectual deference, even abasement, or that purity of intention is the best marker of political nobility. These notions come from somewhere; they have an intellectual history. The sort of people whose personal dialectic culminated in the building of bombs helped gestate these persistent mistakes.