You cannot know what you know until you’ve written it. As you write, you learn what you know—or, more likely, what you don’t know, which, let’s face it, is most everything.
I have hundreds of unpublished drafts for this blog, yet, I’m so happy that I wrote them because I was able to come to a conclusion in my mind. I would have never learned unless I had written.
This reminds me of “Writing is how I think”.