In On Writing... by our very own Stephen King, he writes about The Craft, how it moves within you, how to work with it, but not let it consume you.
One of the most useful and vivid tips that I took away from my first reading of On Writing... was the concept of Constant Reader (or Ideal Reader).
Going back to basics: Why do we read? To be informed or entertained. Conversely, why do we write? To inform or entertain.
Put into a situation wherein you are writing, yet you do not have a known audience, whom do you inform or entertain, then?
King suggests that writers have a default audience, one person who cares deeply about you, your mind, your development as a thinker, and whether your writing hits the desired mark. This person, ideally, is not your teacher or professor, but someone whose only interest in your writing life is that you are doing your best work. Your purest work. Your most honest work.
The goal, when writing, is to leave your reader with exactly zero follow-up questions that are on the same level of depth that the writing is on. Having no known audience in mind, writing to and for Constant Reader will help focus your thoughts, will pull details out that you know you must include to do right by your person, will assure that your expression of ideas is logically ordered, that your diction is as crisp and efficient as possible.
What follows are the spots in On Writing... in which King expands on the concept of Constant Reader / Ideal Reader [NOTE: I took these excerpts from my Kindle version, which I read via the Kindle web reader, so the page references are currently missing. Next time I'm with my heavily annotated copy of On Writing..., I will update this.]
1) ...without Constant Reader, you are just a voice quacking in the void. And it's not walk in the park being the guy on the receiving end. "[Will Strunk] felt the reader was in serious trouble most of the time," E.B. White writes in his introduction to The Elements of Style, "a man floundering in a swamp, and that it was the duty of anyone trying to write English to drain this swamp quickly and get this man up on dry ground, or at least throw him a rope."
2) Grab that book you were looking at off the shelf again, would you? The weight of it in your hands tells you other stuff that you can take in without reading a single word. The book's length, naturally, but more: the commitment the writer shouldered in order to create the work, the commitment Constant Reader must make to digest it.
3) What I want most of all is *resonance*, soemthing that will linger for a little while in Constant Reader's mind (and heart) after he or she has closed the book and put it up on the shelf.
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Someone -- I can't remember who, for the life of me -- once wrote that all novels are really letters aimed at one person. As it happens, I believe this. I think that every novelist has a single ideal reader: that at various points during the composition of a story, the writer is thinking, "I wonder what he/she will think when he/she reads this part?" For me that first reader is my wife, Tabitha.
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She has always been an extremely sympathetic and supportive first reader. Her positive first reaction to difficult ... and controversial [books] meant the world to me. But she's also unflinching when she sees something she thinks is wrong. When she does, she lets me know loud and clear.