How the index changed reading, for better and worse

Index, A History of the. By Dennis Duncan. Allen Lane; 352 pages; £20. To be published in America by W.W. Norton in February; $30

PRODUCING AN INDEX is like squeezing “a grape in a winepress”, wrote a 19th-century French scholar, “so that not even the tiniest drop of precious juice has been allowed to escape”. Reading an index is more like wine-tasting. Take the smallest sip and you can guess the vintage.

Try this one: “gluttony/God/grief/heaven/hell/humanity/Seneca/sex/sin”. It’s a heady combination: ambrosial and intellectual; sensual with a bitter aftertaste. It is from St Augustine’s “Confessions”. Or try a slug of this: “shame/shameless/shamrock/shit/shite/shithouse”. That earthy flavour is from James Joyce. How about “pie/poverty/power/prison/pudding (see ‘Christmas Dinner’)/ pugilist”? Full-bodied, with a hint of festive spice: Dickens, naturally.

Indexes are to books as menus are to meals: often the best bit. The index should be prosaic—it is, after all, a mere tool—but it can read like poetry. Even John Betjeman, a bard of Englishness, might struggle to match “Abingdon/al-Qaeda/Angola/Ascot/Asda”. Indexes are a solution, but they are also a puzzle. Take that last one. It is from a biography of John le Carré—and who wouldn’t wonder, Smiley-like,...