Q: Your second book is An Enquiry Concerning Human Understanding by the 18th-century British philosopher David Hume. You read this in college and it really changed your life.

A: Yes. I was at that stage, a college sophomore or thereabouts, when you’re searching around, looking for belief systems. I think it’s actually a point when you’re quite vulnerable, because you are looking for someone who is going to offer you all the answers. Some people turn to religious orthodoxy, other people turn to Ayn Rand. One of my favourite lines – and I haven’t been able to find out who came up with it – is that “There’s an age when boys read one of two books. Either they read Ayn Rand or they read Tolkien’s Lord of the Rings. One of these books leaves you with no grasp on reality and a deeply warped sense of fantasy in place of real life. The other one is about hobbits and orcs.”