Aldous Huxley’s very funny first novel, “Crome Yellow” (1921), features not just a varied smattering of invisible books and books-in-progress (Mr. Barbecue-Smith’s “Pipe-Lines to the Infinite,” Henry Wimbush’s history of the town of Crome), but what might be called second-degree invisibles: a bookcase of pageless spines — 10 volumes of “Thom’s Works and Wanderings,” seven of “Tales of Knockespotch” — camouflaging a secret door.