“May all your teeth fall out except the one that gives you pain”: It’s an old Yiddish curse, but as Fintan O’Toole explains in his slyly brilliant new book, it could turn out to be an apt description of the “English nationalist project” known as Brexit. An unsettled sense of national identity is like having a sore tooth, and Brexit is like taking a sledgehammer to the wrong side of your face. Once the “radically invasive” procedure of extracting Britain from the European Union begins in earnest, O’Toole writes in “The Politics of Pain,” the original toothache will persist — only this time amid the wreckage of a bloody mouth.

O’Toole, an Irish journalist, is aware of the political and economic upheavals that have buoyed pro-Brexit forces, but with this book he explores what the critic Raymond Williams called a “structure of feeling” — in this case, a mentality that likens the staid bureaucracy in Brussels to a monstrous occupying force. O’Toole dissects a number of myths peddled over the years by Britain’s most extreme Euroskeptics, including the specter of an overweening continent determined to outlaw prawn cocktail-flavored potato chips.

Brexit and President Trump represent both sides of the Anglo-American nationalist coin — on this minimal observation, O’Toole and Rich Lowry, the editor of National Review magazine and the author of another new book about nationalism, would seem to agree. But where O’Toole warns of the dangers posed by indiscriminate eruptions of nationalist fervor, Lowry’s “The Case for Nationalism” exudes an untroubled sanguinity. Nationalism’s biggest problem, Lowry says repeatedly, has been the “smear” against it.

Image Fintan O’Toole, author of “The Politics of Pain.” Credit... Benson Russell

“The Politics of Pain” is searching and elegantly argued. O’Toole isn’t unsympathetic to those who voted in favor of Brexit, but makes abundantly clear that he believes they were suckered into a raw deal. Being Irish, he knows “the worst agonies that zero-sum nationalism can inflict.” His tone is charmingly wry but never gleeful. He reserves his most withering indictments for elite politicians like Nigel Farage and Boris Johnson — the “Brexit ultras” who successfully deployed the language of autonomy and wounded pride to cast Brexit “simultaneously as a reconstitution of Empire and as an anti-imperial national liberation movement.”