This quote comes from a favorite little book of mine called The Little Zen Companion. The book is only slightly larger than my palm, but is thick. On each page are thought-provoking little quotes from Eastern AND Western philosophers. And yes, Yogi Berra and Mark Twain ARE quoted in there if you were wondering. Heh.
I was thinking how the above quote would apply to fanfic and canon (among many other things in life). And the evolution of XF fanfic over the years. How fanfic that was plausible back in the days of yore is completely ridiculous today. That kinda thing. There was a thread at Haven that touched on this subject. An XF author wanted to just write a MSR in S1 and her beta told her that was non-canonical.
To me, this author will always have a "beginner's mind" no matter how many years she writes. Ironically, there is a bit of self-awareness there as she recently referred to herself as a newbie after at least 5 years of hanging around the fandom.
Yet, I dispute that the expert's mind has few possibilites. The expert does know what cannot be done, hence the possibilities are limited. However, that expert can go places the beginning mind may not even contemplate. Beginners often trod down well-worn roads for they know not what has been done. Experts can trailblaze.
I'm not saying that a beginner cannot trailblaze, it's just less likely they would. I know this concept is supposed to fall under the idea that a honey bee can fly 'cause nobody told it that it can't. It's just that the honey bee is the exception to the rule. We love those exceptions.
George Carlin has a great quote about children, who are the ultimate beginners. I'll paraphrase, 'cause I can't remember it exactly. Children are like everybody else, some are great, some are good but most are just losers.