Another classic quote from Shunryu Suzuki on the Zen idea of a Beginner’s Mind:
If your mind is empty, it is always ready for anything, it is open to everything. In the beginner's mind there are many possibilities, but in the expert's there are few.
Of course there are all sorts of directions one can take this quote. It came up in the discussion of Goldratt’s The Choice where one of the pillars of having a full life is to “Never say, ‘I know.’” Always look for surprises or new opportunities to learn. In the case of our traditional view of “the expert,” if they believe they know, then there is less chance that they will see.