The idea that the English have a national character sounds plausible enough, until you start to try to pin it down. Are the English the romantic, imaginative people of Shakespeare and Keats, or the efficient imperialists who lorded it over India and Africa? The introverts whose motto is “No sex please, we’re British,” or the swingers of Carnaby Street and Cool Britannia? The sneering redcoats of the American Revolution, or the plucky Londoners of the Blitz? Is the archetypal Englishman John Bull, or Colonel Blimp, or Monty Python? Whoever he is, it begins to look like he has a split personality: he is an adventurous homebody, coldly sentimental, genteelly vulgar. As Daniel Defoe wrote more than 300 years ago, “from a mixture of all kinds began / That het’rogeneous thing, an Englishman.”

The only thing all these myths of Englishness have in common is the premise that there is such a thing as the English character — an enduring national essence that separates the people of the sceptred isle, for good or ill, from their fellow men. But for Peter Mandler, Englishness is less an essence than a mirror, in which observers of every stripe see their own images. In “The English National Character” (Yale University Press, 348 pages, $35), Mr. Mandler is not out to define that elusive concept, but to see how generations of English and foreign writers have defined it, argued about it, and finally, perhaps, discredited it. In the process, his densely informative work offers a superb example of how to write, in the words of his subtitle, “the history of an idea”