Hamlet showed “method in his madness” but the same cannot be said of Don Quixote. When the Knight of the Mournful Countenance is interviewed late in the novel by Don Diego de Miranda, that worthy sees him “as a sane man with madness in him, and as a madman with the same tendencies,” in John Rutherford’s translation. Don Diego was especially puzzled because what Don Quixote said “was coherent, elegant and well expressed, and what he did was absurd, foolhardy and stupid.”

“Hamlet” was first performed in London in 1601 and the first part of “Don Quixote” appeared only four years later, in 1605, but there the resemblances end. Hamlet’s dissembling may lead to madness — opinions on this differ — but Don Quixote is splendidly delusional from start to finish. It might seem risky to draw conclusions about national character on the basis of two fictional characters. But Spaniards revel in the risk. There are no hesitating Hamlets in Madrid. For four centuries now, with somber pride, they’ve thrown their lot in with the windmill-tilting hidalgo.

In “Imagining Spain: Historical Myth & National Identity” (Yale University Press, 256 pages, $38), the well-known and prolific historian Henry Kamen examines the fierce hold this and other myths have exerted over the Spanish mind since the late 15th century. In seven trenchant chapters and a postscript, Mr. Kamen demolishes one cherished fantasy after another. Drawing on archival sources, unpublished manuscripts, and a vast body of scholarship in several languages, he takes a fresh, and often scathing, look at Spanish notions of nationhood, monarchy, and empire, and shows them to rise almost wholly out of ignorance and self-delusion.

Mr. Kamen’s chapters on Spanish Christianity and the Inquisition are especially provocative, but it is probably his sobering chapter on the Spanish language, and the grandiose claims made for its universality in both the past and present, which will most outrage Hispanophiles. Not only was Spanish, at the height of Spain’s imperial power, second to Italian in prestige as well as currency, but missionaries failed by and large to impress it upon subject peoples. In Peru, 400 years after the overthrow of the Incas, Quechua remained the dominant language; in the Philippines, only 5% of the population had learned Spanish by 1898, when the islands came under American rule. (Within a few decades of the takeover, by contrast, some 26% of Filipinos had learned English.)

Mr. Kamen devotes his final chapter to the beloved Spanish notion of “cultural decline,” a constant for centuries. For most Spanish authors, the country has been in a continual free fall into “decadence” since the Siglo d’oro, or Golden Age — roughly the late 15th and early 16th centuries — and especially since the reign of Ferdinand and Isabella (though some of the more melancholy commentators saw even this period as fraught with tragedy). The causes for this “decline” are slippery and shifting. The stultifying effects of the Inquisition or the imposition of foreign rule — the Habsburgs in 1516, the Bourbons after 1700 — or the Napoleonic invasion of 1808, as well as the Spanish-American War of 1898 and the loss of Spain’s overseas territories (widely viewed as a national catastrophe), are routinely trotted out as causes. Not one of these explanations holds up against the evidence Mr. Kamen assembles; and yet, they have been — and still are — invoked by nationalist authors simply because they are irresistible. In the process, they have become self-justifying myths. As Mr. Kamen mocks them, “If a Spaniard was not the inventor of the electric light bulb, it was because of the Inquisition.”

In his “Meditations on Quixote” of 1914, the Spanish philosopher José Ortega y Gasset remarked of his countrymen that “we prefer the lively sensation of things to the things themselves.” That is, of course, the very problem Mr. Kamen addresses. But what makes his book so interesting is that he also shows, almost in spite of himself, just how oddly dynamic and even entrancing these “lively sensations” proved to be over four centuries of incessant kvetching and posturing by Spaniards of every party and class. The myths may not stand up to scholarly scrutiny, but they did provoke some fine, and highly quotable, brawls.

While Mr. Kamen has great fun with these myths, he is quite relentless — as well as fearless — in dismantling them. Not surprisingly, he has been roundly denounced in the Spanish press for his pains. And no wonder: The effect is as if poor, raving Don Quixote were not simply given a cold shower but strapped to a gurney for a series of electroshock treatments. And yet, only someone who loves Spain deeply could have written this book. By stripping away the corrosions of myth, Mr. Kamen shows a Spain as rough-and-tumble as it is various — not the “lively sensation,” but the thing itself.

It goes without saying that “Imagining Spain” is a supremely quixotic book. It tilts at some dangerous windmills. But as Don Quixote himself said in explaining himself to Don Diego, “it is better to lose the game through scoring too many points than through scoring too few.” And sometimes, of course, the windmills really are monsters in hiding.

eormsby@nysun.com