You’re sitting at your desk, two hours into the working day, and you get the urge . You suddenly feel deeply unhappy about staying still. You want to get up and go for a walk. You want to talk to a colleague. Anything to get away from this static, boxed-in workstation. For two hours, you’ve been perfectly content to tap, tap away at your computer, but now, your chair feels like a prison, and the keyboard feels like a chain. These moments of sudden restlessness come for all of us sooner or later. It might be at 11 a.m. on a Tuesday, but it could also be three years into a new home or too long without a holiday. And this itchy-footed, dissatisfied need to move and to change has a German word: zugunruhe . Flight lust In this week’s Mini Philosophy interview , I spoke with the nature writer Rob Macfarlane about The Book of Birds , and I asked him about migratory birds.…