I wake and see through my bedroom doorway that the kitchen light is on. The kitchen light shouldn’t be on. Like most people, I have a nightly routine. The kitchen light’s the last thing I switch off before going to bed. Now I wonder if I’ve forgotten to turn it off, or if there’s somebody in my little flat. Which is the likelier possibility? I might’ve forgotten to switch off the kitchen light. It’s possible, because everything is possible. But it’s unlikely. I’ve never forgotten it before. Also, I would not only have to forget to switch it off, but then jump into bed, switch off the bedroom lamp, and…