I'm starting to feel a bit important... I can tell because I'm getting free books in the post! Mostly so I can prepare for talks I'm sharing with other people, and intelligently say "Bruce! This book you made with Allan Ahlberg recently is a very good example of what we're talking about, especially the bit with the pencil!"
I did really enjoy this book very much, it was the perfect book to read before breakfast, getting ready to face the universe yet again.
It is all about the responsibilities of world creation, or: how to look after your art materials, especially rampant erasers.
It's an encouraging book: it makes you want to make your own book straight away. And it's honest: it shows that creating things isn't just fun - it's also tiring and scary at times, and it's supposed to be that way. That's something you need to know to fully enjoy creativity, and ultimately very reassuring.
I would have kept this under my pillow when I was little.