understate the difficulty ... A system cannot truly postulate its own consistency, quite apart from questions of analysis and justification [Gödel's theorem - An incomplete guide to its use and abuse, p. 125]The point could also be made by correcting the psychological metaphors: the limitations in question do not concern so much the ability to know (prove), but the ability to imagine (postulate); to put it in idiot rhyme:
If I could imagine myself,
I wouldn't be me,
consistently.
On the other hand, Franzén presents a good case for concluding that
the human mind, if it is at all like these formal systems [PA or ZFC], is able to understand itself wonderfully.The conclusion follows from the ability of such systems to reflect their own abilities and disabilities to prove facts about every finite subset of their axioms [p. 125-6].