The eponymous 18th-century artist, an engraver who dreamed of becoming a great architect, is the metafictional narrator of this quirky, discursive novel by the German author of the equally rarefied There Is No Borges (not reviewed). Köpf’s Piranesi is a mental traveler who inhabits, not just his native Italy, but the civilization of ancient Egypt and the Australian desert, as well as the historical present, while pontificating about his own aesthetic passions and hatreds (the latter conveniently subsumed in the disagreeable figure of Piranesi’s contemporary, the notoriously fastidious art critic Winckelmann). This impressively learned, ineffably ponderous self-portrait of “an emotionally crushed . . . embittered and disappointed man to whom his life’s work has been persistently denied” has its lively moments (often upstaged by the novel’s many longueurs), but bile is not enough—at least when it’s this arty.