"the map is not the territory" has stuck in my mind as one of the over-arching principles of rationality. it reinforces the concept of self-doubt, implies one should work to make their map conform more closely to the territory, and is invaluable when one believes to have hit a cognitive wall. there are no walls, just the ones drawn on your map.

the post, "mysterious answers to mysterious questions" is my favorite post that dealt with this topic, though it has been reiterated (and rightly so) over a multitude of postings.

link: http://www.overcomingbias.com/2007/08/mysterious-answ.html