from Writing Down the Bones: Freeing the Writer Within by Natalie Goldberg:
“A responsibility of literature is to make people awake, present, alive. If the writer wanders, then the reader, too, will wander. The fly on the table might be part of the whole description of a restaurant. It might be appropriate to tell 
precisely the sandwich that it just walked over, but there is a fine line between precision and self-indulgence.
“Stay on the side of precision; know your goal and stay present with it. If your mind and writing wander from it, bring them gently back. When we write, many avenues open up inside us. Don’t get too far afield. Stay with the details and with your direction. Don’t be self-absorbed, which eventually creates vague, muddy writing. We might really get to know the fly but forget where we are: the restaurant, the rain outside, the friend across the table. The fly is important, but it has its place. Don’t ignore the fly; don’t become obsessed with it. Irving Howe wrote in his introduction to Jewish American Stories that the best art almost becomes sentimental but doesn’t. Recognize the fly, even love it if you want, but don’t marry it.”
What excellent advice and how well the metaphor of the fly is handled. And how difficult I found it’s been over four decades of writing to follow this advice, which editors have given me, both gracefully and bluntly. What I’ve learned to do is go ahead and put the fly into the copy with his gritty, sticky legs and his all-seeing eye and his peripatetic tour of everybody’s food, and having gotten it out of my system, go back and take most of it out after I ask myself, “Why are you putting it into the story in the first place?” The exercise of writing about the fly usually answers that question and the answer is often not a good one: “Because I can and want to.”
Thanks for this post! You have to know where you’re going to get there.
But I find that I have to write the thoughts to keep them coming. Then edit later. My internal editor isn’t good at generating first drafts and if I let her dictate, we’re stuck.