why write
You get more revolutions with your ideas.
You have this idea in your head. When it first emerges, it's scrappy; it's unpolished. Through process—revolutions—your idea passes through the refinery and comes out the other end as obtained understanding. Writing gets you more revolutions with that idea.
process
Your first words are usually bad. From iterating and reflecting, you start to see gaps between sentences or jumps between premises. The unfinished work boggles your mind, and your curiosity forces you down a rabbit hole to clean it up. By the end of it, your thoughts crystalize more strongly, and even spawns new ideas through association.
As time goes by, you find new inspiration. Whether from shower thoughts, Pinterest, or a new book, you return to that draft and entertain your ideas once more. This sounded a bit off. This could be added in. This is unnecessary detail. And all of this is magnified, especially if you're hyper-obsessed over details.
If you strive for clarity, your thoughts become more precise through due process.
publishing
When you put your writing out, you assert them. You are, at least until the point of publishing, held to a degree accountable to them. Standing in front of a stage makes ideas stick.
Many will resonate with your work, and many won't. But, the best gift you'll get is good criticism because it invokes an unaccounted-for perspective. And, once more, you go back to that idea. Your perspective grows.
Writing is perhaps even necessary for achievement. The emerge-iterate-refine cycle creates copious reflections and revisions through which we learn. Writing lots, seen or unseen, unlocks feedback loops, cycles of revolutions that provide insight and perspective—you become more competent.
plz write.
It’s not that writing has to be the medium of reflection, but that there must be some medium that is rooted primarily in reflection rather than craft. And writing has a distinct quality of being rooted in simplicity, clarity, and a core message. - Anu Atluru
In precisely defined domains it's possible to form complete ideas in your head. People can play chess in their heads, for example. And mathematicians can do some amount of math in their heads, though they don't seem to feel sure of a proof over a certain length till they write it down. But this only seems possible with ideas you can express in a formal language. Arguably what such people are doing is putting ideas into words in their heads. I can to some extent write essays in my head. I'll sometimes think of a paragraph while walking or lying in bed that survives nearly unchanged in the final version. But really I'm writing when I do this. I'm doing the mental part of writing; my fingers just aren't moving as I do it. - Paul Graham