I don't agree that he puts it all that brilliantly.
Does the fish question it's own limit of understanding ? There is a fundamental difference in not knowing something and knowing that you don't know.
If you were wandering around the outback and didn't realise you were lost, you'd likely die. If you knew you were lost you may take steps to help yourself. Those very steps may lead you to discover a way to save yourself. It's the realisation in the first instance of what you don't know that provides the impetus to eventually resolve the issue.
