"She could see it all so clearly, so commandingly, when she looked: it was when she took her pen in hand that the whole thing changed. It was in that moment's flight between the picture and her canvas that the demons set on her who often brought her to the verge of tears and made this passage from conception to work as dreadful as any down a dark passage for a child." -- description of the character Lily Briscoe, struggling with her painting in To the Lighthouse
In art there is a term: disegno. Today's dictionaries define it directly as drawing or design. Back in the day (Michaelangelo's day), however, it referred more to the entire process of art. First a piece was conceptualized in the brain-box and then the artist would make a physical representation of their vision.
There's a glitch that often occurs in this process: the physical representation ain't nothin' like what the brain-box came up with.
I don't know about you guys, but when I get an idea for a story it's rarely fully formed. I have an image or a character or a plot twist in mind--then I go to write it down and POOF! It's suddenly something else.
This is frustrating. Ya know?
I realize that this is because the story isn't fully formed when I begin and that of course things are gonna shift around. But it's also because the act creating a thing changes the thing. There are a multitude of reasons for this (including, but not limited to: skill-level, tool effectiveness, and your ability to assess the potential obstacles and overcome them).
As a writer, the medium is restricted because you are limited to words--in this visual lifestyle we live in, sometimes it's hard to translate what you see in your mind's eye to a word-medium. Artists are limited by the materials that they have. Forget to buy yellow? Well, that pause to go buy it might jack-up your palette. Are you a sculptor? Your tools' sharpness, the flexibility of your wrist, etc., all affect the end result.
And do you know your limitations? Are you aware that, by not having visited Italy, nor being related to anyone Italian, or not having a second cousin's friend's brother's Italian grandmother make you meatballs, your descriptions of a immigre grandmother having an emotional meltdown because she misses the homeland while making homemade pasta might be cliched somehow? (I don't know how...but maybe.) And, being aware that this might (somehow) handicap you, do you have a strategy to avoid cliches?
If that last paragraph made any sense to you at all (see? Brain-box to blog-typing is not always in sync either), then that leads me to my point.
The great artists/writers/etc. understand their tools, their resources, and their limitations. They come up with solutions to give their pieces a closer resemblance to what was originally in their brains.
And I think that they also recognize when a piece they're working on is better than what was in their brains.