[redpoint5]

It's easy to see when you're smarter or more knowledgeable than someone else who is less knowledgeable, but extremely difficult to tell when you're the one lacking understanding.

Understanding isn't some easy or trivial thing; it requires intense concentration at length, and usually all that does is expose how infinitely complex the subject is, rather than give a sense of mastery.

Perhaps the most reliable way to tell if someone is (un)knowledgeable is if they say "the solution is easy".