Emily Thomas is a distinguished academic philosopher who has ‘spent a lot of time by herself getting lost around the world’. Here she takes a trip to the wastes of Alaska and uses it to launch an extended meditation on a compelling question: what does it mean to travel? What is the significance of our urge to set off around the globe — not for trade, not to fight or conquer, but for its own sake?

By narrowing her remit thus, Thomas begins in 17th-century Europe, with the restless spirit of the Enlightenment.