 He said to him, you know, I don't believe in you. I mean, the ghost is quite taken aback. Why don't you believe in me? And Scrooge's answer is basically, well, you know, you could be caused by indigestion, for example. So essentially that you could be some sort of figment of my imagination that's caused by some kind of imbalance in my system, essentially. But Dickens used this far more humorous way of talking about it.