Birds should not teach bats how to fly.

Yet, too many teachers, if you give them this as an exercise to teach this unsolved problem they will go and they will work at this at home and they will try to solve it. So that they can go into the class the next day and they already know the answer...

Beauty over truth.

As a mathematician you probably think of me as someone who wants truth. No, no, no, I want beauty, I want to express the beauty of mathematics, and this is not it. (Referring to boring worksheets, repeating the same skill).