Colourful!

For want of anything better to do, I bought one of these "mindful" colouring in books. I'm not into this mindful stuff as I don't really understand it. I couldn't get yoga either!
One of the schools I worked in, when I allowed the kids to colour something in the boss used to say "they don't learn anything from colouring in" Yet here are adults falling over each other to buy books just to colour in!!. I'm stumped.
I wonder what you can tell about a person by their choice of colours. That will be the next development.. psychologists analysing our choice of colours!!