One of the most frequent bits of advice writers hear is to "write what you know."
Frankly, I think that's terribly limiting advice. Why write what you already know? Why not write what you want to know? What you would like to learn about? What you've never had the chance to think about before?
That's not to say there's no value in experience. To an extent, we are always writing what we know. I think that's where subtext comes in. You create something new and relate it to something old. That's where magic happens.
I have learned so much from writing. I've read countless books I would otherwise not have read, some of which are even reviewed here on the blog. Books about grief, books about brotherhood, books about twins - all informed my writing. And that's just for one project.
Books about the treasures of the pharaohs, books about quantum physics, books about Harry S Truman - all were things I wanted to know, things I wanted to write about. With luck I'll get to all of them!
Not that anyone really reads this, but if one day someone does come across this, I challenge you: write what you don't know. Go find out about it and make something really amazing come of it.