All is Vanity by Charles Allen Gilbert
There are two phases of writing, according to Stephen King: door shut and door open. When the door is shut it's just you spewing forth your first draft. That first draft is pure self-indulgence, and should be; it's whatever your imagination and subconscious and conscious and ego and vanity and id want to spew. It's as pure as both a daydream and a tantrum.
The second phase, door open, is when the work begins. That's when you have to consider who you are writing for. That is when you step outside yourself, away from your reflection and your own preciousness, and begin to tear down and pare down, to kill paragraphs and paragraphs of darlings, to ask yourself questions that could dissolve the whole structure of your cherished idea like hot tea poured on a kingdom of sugar.
But that's not all a writer deals with when the door is open. We also get criticism, rejection, support from important people whipped out from under us like a tablecloth trick, leaving us tipped over and shattered, and endless microaggressions like shards of crystal to crawl over on our way back to the table to start again.
This is why writers need each other, like the good friend who catches you talking to yourself in the mirror and does not think you strange at all, does not mock, is not critical or embarrassed for you or by you. Instead this friend sits beside you and looks at herself in the same mirror, speaking from her reflection to yours, playfully, gently, with shared joy in that most delicate of moments.
Other writers, like that rare friend, understand.
In that mirror, as we play and imagine, it is not all vanity. In that mirror we create worlds.