I try to cheer Wilson up by suggesting he incorporate 'Doctor Vermilingua's Healing Ant Soup' into his portfolio of medical specialities, perhaps even naming it after his mother, but he is not enthusiastic. He shuffles off disconsolately, telling me he's going to read a magazine. 

Later I took him a cup of tea and a biscuit and discovered he was reading New Scientist: The Existential Issue. It's full of questions like 'How Do I Know that Everyone Else Isn't a Zombie?', 'Am I a Hologram?' and 'How Do I Know I Even Exist?' with answers like 'You Don't', 'You Probably Are', and 'You Can't' respectively.

This is not a good sign.