Does the adjective "centoesque" exist? If not, it should, for Robert Irwin's ingenious historical fantasy "Wonders Will Never Cease" is a contemporary novelist's version of the poetic form known as a cento. Because the Middle Ages valued tradition over originality, erudite versifiers sometimes devised poems in which every line was borrowed from some previous work of literature. While reading a cento, one savored its imaginative repurposing of bits from Horace, Virgil and any number of lesser ancients. We see the remains of this tradition in allusion-filled modern works such as T.S. Eliot's "The Waste Land."

Throughout "Wonders Will Never Cease," Irwin embeds lines and episodes from dozens of poems, legends and medieval romances. Some of these are ­acknowledged by name, others aren't. The sources easiest to spot include the tale of the giant Bran and the Welsh king Matholwch, the legend of the Wild Hunt, the sea-voyages of St. Brendan, "Sir Gawain and the Green Knight," "Jack and the Beanstalk," Thomas Malory's "Le Morte d'Arthur," "The Song of Roland," "The Nibelungenlied," the poetry of Dante and Francois Villon, Julian of Norwich's "Revelations of Divine Love," and, of course, "The Arabian Nights."

I say "of course" because Irwin is most widely known as the author of "The Arabian Nights: A Companion" and several other excellent books about Arabic culture. Yet Irwin is hardly a dry-as-dust antiquary, and "Wonders Will Never Cease" frequently reveals the wide range of his reading: His description of the world's end was obviously adapted from H.G. Wells's "The Time Machine," and there's even an allusion to — shades of Sherlock — "a Red-Headed League."

Irwin's novel itself is set during the 15th-century's War of the Roses — the same conflict that inspired "A Game of Thrones"— and virtually all its main characters are historical figures. If you remember your Shakespeare, you will detect in these pages the backstory for "Richard III." This is a time when "genealogy and heraldry are the only two sciences worth knowing."

The book's action focuses on Anthony Woodville and his family: His sister Elizabeth eventually weds King Edward IV. In the first chapter, this young soldier undergoes an after-death experience during which he glimpses a strangely quiet procession and an old man with a bleeding wound. Only much later does Anthony realize that he has been vouchsafed a vision of the Grail King.

He also starts to see ghosts, so he visits the Abbot of Crowland for advice. As it happens, the Abbot and his monks have been temporarily stymied in calculating how old our world is:

"It now seems that there are too many centuries to fit their estimation of the age of the earth. However, after much thought and the consultation of old chronicles, the Abbot has succeeded in con­clusively demonstrating that most of the centuries between 600 Anno Domini and 900 Anno Domini have been invented by a 10th-century Chronicler working for the German Emperor Otto III. These centuries were conjured up by him so that, when the year 1000 began, Otto could be hailed as the apocalyptic Emperor of the Millennium. . . . It was most suspicious how very little happens in those phantom centuries and, once they have been done away with, the Abbot's chronology works perfectly."

Anthony eventually encounters Sir John Tiptoft, discovering that "The Butcher of England" is a cultivated bibliophile whose conversation is laced with surreptitious quotation. When Tiptoft declares, "People prate about how wonderful life is, but I swear to you that reading is better," one hears an echo of Logan Pearsall Smith's famous remark, "People say that books are the thing, but I prefer reading." Recalling his time in Rome, Tiptoft — who practices sorcery — mentions one night when "I had passed barefoot friars celebrating vespers in a ruined temple and I could still hear their singing as I began my conjuration." Edward Gibbon is the source here: "It was at Rome, on the 15th of October, 1764, as I sat musing amidst the ruins of the Capitol, while the barefooted friars were singing vespers in the Temple of Jupiter, that the idea of writing the decline and fall of the city first started to my mind." When Tiptoft confesses that he is "vowed to the service of the God that has failed," readers may remember a once-
celebrated collection of essays about communism, "The God That Failed."

In every way possible, Irwin blurs story and history, fantasy and reality. "Our earth," says the Abbot of Crowland, "has trapdoors that are hidden and strange things go in and out of them." There's a talking head that can predict the future, an unfunny jester name Scoggin, fearful revenants, lovers who only couple in churches, a magnificent falcon used as a messenger from the land of the dead, a Secret Library, a dragon that guards an enchanted sword, Chaucer's lost "Book of the Lion" and a Museum of Skulls. The wonders never cease.

But neither do they go on for too long. Irwin keeps the action fast-moving and even somewhat schematic, though his few details can be telling. Describing the funeral of Anthony's witchy, fairy-
obsessed mother, we are told that "just outside the churchyard there seem to be small children hiding in the bushes and whispering."

Stories within stories within stories. King Edward's alchemist and spymaster — his name is Ripley, believe it or not — tirelessly spreads "fake news" about Anthony, portraying him as a hero out of chivalric romance. But, as Sir Thomas Malory tells the young man, "it is not a comfortable thing to be a creature in someone else's fictions." True enough, but as Tiptoft also reminds us, "Search how you may you will never find happy endings in life. It is only there in books." And sometimes not even there.

Michael Dirda reviews books every Thursday for The Washington Post.

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wonders will never cease

By Robert Irwin

Arcade. 351 pp. $25.99