One advice from the book is to train your eyes to see things on streets. Thomas advises you to pick one colour -- any colour -- and try to see that colour throughout a day. I tried that today. I randomly chose red. Suddenly it was red everywhere all around me! I could see so much red that I thought I should pick a different colour. So I told myself that I would see yellow. Now I started seeing yellow everywhere, as much as there was red. It's amazing how I don't see any of these colours when I don't want to see.
This exercise gave me a new experience, but my mind said this was just another variant of two different ideas I already have. I could rationalise and see this experience as a proof to those ideas. But I suspect that it's just my mind playing games with me and making me see only what I already know. Maybe knowledge is, like everything else, both an asset and a liability.