And it's best if you know a good thing is going to happen, like an eclipse or getting a microscope for Christmas. And it's bad if you know a bad thing is going to happen, like having a filling or going to France. But I think it is worst if you don't know whether it is a good thing or a bad thing which is going to happen.

Eventually scientists will discover something that explains ghosts, just like they discovered electricity, which explained lightning, and it might be something about people's brains, or something about the earth's magnetic field, or it might be some new force altogether. And then ghosts won't be mysteries. They will be like electricity and rainbows and nonstick frying pans.

But I said that you could still want something that is very unlikely to happen.

Sometimes we get sad about things and we don't like to tell other people that we are sad about them. We like to keep it a secret. Or sometimes, we are sad but we really don't know why we are sad, so we say we aren't sad but we really are.

I have very fond memories of swimming in Walden Pond when we lived in Boston. You'd swim past a log and see all these turtles sunning themselves. Slightly disturbing if you thought about how many more were swimming around your toes, but also rather wonderful.

No one wants to know how clever you are. They don't want an insight into your mind, thrilling as it might be. They want an insight into their own.

I've worked in television long enough to know that when you stop enjoying that type of thing you go home and do something else.