"This is ridiculous, I mean, wholly ridiculous. It never did any child any harm to have something that was a tiny bit above them anyway, and I claim that anyone who can follow Doctor Who can follow absolutely anything"

This quote by Diana Wynne Jones is describing the idea that kids ought to be exposed to material that is slightly above their current level of understanding. She believes that this is helpful for kids, as it encourages them to think seriously and expand their understanding. She uses the example of Doctor Who, a popular British science fiction tv series, to highlight her point. She argues that if a kid can follow the complex stories of Doctor Who, then they can follow any material. She thinks that this exposure to more tough product will help kids grow and develop. Overall, Diana Wynne Jones is advocating for kids to be exposed to product that is a little above their existing level of understanding, as she believes it will assist them grow and develop.