It was a cranky observation on the letters page of a news weekly, right after New Year's: "Your list of books of the year (December 7th) left me wondering when exactly, in the history of book publishing, did it become mandatory for all non-fiction titles to include a colon and a subtitle?"
When I checked the list, which I had clipped for reference, I saw that almost all the books on it indeed had a colon in their title. It functioned as fulcrum, balancing the pithy main title, which serves as a teaser, with what comes after, an explanation of what the front bit is supposed to mean.
Thus "Lean In: Women, Work, and the Will to Lead," Sheryl Sandberg's take on why women are still underrepresented in the halls of corporate power. The front part is an imperative phrasal verb, used in a very specific way. Ms. Sandberg deserves credit for introducing a whole new usage.
But without the subtitle, the book would have gotten lost in the tide of new books. A book called simply "Lean In" would have been like a letter dropped into a mailbox with a street address but no ZIP Code.
One book on that list that did not have a colon in its title might have benefited from one: "Thank You for Your Service," by David Finkel. The title sounds ironic or maybe a bit snarky, but the book is a well-received study of the lives of American soldiers returning from combat.
The formula here is "Short Word or Phrase: Some Words (Sometimes a Lot of Words, Actually) That Convey the Gist of the Book." Thus we have Brendan Simms writing on "Europe" – a subject that has been addressed before – plus "The Struggle for Supremacy, from 1453 to the Present." (We're supposed to recognize 1453 as the end of the Middle Ages.)
A look at the blurb on the book, though, suggests that its main argument would have been better captured by a subtitle reading "How Germany's Power Has Been Worrying Its Neighbors Since the Beginning of Modern Europe."
Doris Kearns Goodwin, in titling her latest book, "The Bully Pulpit: Theodore Roosevelt, William Howard Taft, and the Golden Age of Journalism," had the advantage of a pre-colon phrase that telegraphs "Teddy." But one can't help observing that with all the characters she alludes to after the colon, that pulpit must have gotten pretty crowded, especially with Taft in there, too.
Ian Williams of The Guardian identified the trend toward "colonization" a few years ago and surmised that it was the result of publishers wanting "to put as many keywords in the title as possible to get the click-on traffic for online buyers." He imagined how Herman Melville's masterpiece would have been titled in the 21st century: "Moby Dick: How Ishmael Lost His Shipmates and Found His Soul While Chasing Jungian Archetypes Around the Globe and Carrying Out Experimental Marine Mammal Research."
Of course, all these colons are not necessarily visible on the covers of these books. Book jacket designers achieve the equivalent of punctuation by using different fonts and colors instead. Colon originally meant an independent clause. Later it came to mean the punctuation mark that signals a clause coming up.
As an inevitable feature of serious nonfiction, the colon might seem to be something of a tic. But a look over a list of notable books suggests that it would be hard to do without it.