For a book that consists so largely of summary accounts of political madness and murder, Black Mass is surprisingly exhilarating. That may be the result of its almost equally surprising organisation. Two or three very large and very general claims frame the book: that politics is a form of religion, that apocalyptic fantasies have been the stuff of Western politics since the Middle Ages and continue to be so now, that the restoration of peace requires a combination of political realism on the one hand, and on the other an acceptance of the need to accommodate in public life the non-rational needs that religion satisfies.

Within that framework, Gray takes aim at a wide range of targets. By no means everything he says is plausible, but even at his most unpersuasive, he is invigorating. Readers of a certain age will be reminded of Norman Cohn’s The Pursuit of the Millennium, but where Cohn wrote in