A few weeks ago I was in a maths lecture, and the lecturer was, as is fairly standard, writing proofs from his notes as he went. He then mentioned one of the ex

A few weeks ago I was in a maths lecture, and the lecturer was, as is fairly standard, writing proofs from his notes as he went. He then mentioned one of the exercises, explained the proof strategy for it, and then started to actually write out the proof. After five or six lines he stopped, scratched his head, looked at the proof, and crossed out the last line he'd written. Then he looked at it some more. After a couple of minutes he looked up, apologised, and said he'd got stuck and that we'd go back over it in the next lecture. It was a great relief to me that my own struggles were not the result of laziness or stupidity: some things are just hard, and take a while to get right, and it's rare to be able to write down something in its correct form on the first pass.