“Challenging Assumptions” has become a cliche. Very few know how to do it well. Fewer know how to teach the technique as well as Edward De Bono.

There was a nip in the air. I was enjoying my brisk early morning walk. As I was turning round the garden, I saw some one crossing the road and coming towards me. It was a seventy-year-old man. He was trim, and looked very smart in his walking attire. He had what many would call [...]