Isn't it fun to memorise conjugation tables for verbs in a new language? Well, no, not unless you're Robert Lane Greene, a business correspondent for The Economist and editor of our Johnson blog. My esteemed colleague and self-described office language nerd has written a book, "You Are What You Speak", about "grammar grouches, language laws and the politics of identity". Here he talks to our books & arts editor about the hardest language he has ever tried to learn (Arabic), why English has spread around the world (and how it helped Shakespeare), and why there's no such thing as a truly primitive language.