A song you wrote alone in a room belongs only to you until the first time you play it for someone else. After that it belongs to whoever was listening, and you become — at best — a courier.
It's a strange thing to make peace with. You write a song about a specific room and a specific person, and a year later someone in a city you've never been to tells you it got them through something you couldn't have guessed at. They aren't wrong about what the song is. They are usually right about it in a way you weren't.
The songs that last are not necessarily the ones you tried hardest on. They are the ones you left a little porous. The ones with enough room inside them that someone else's weather can blow through. If a song is too sealed — too specific about what it means and who it's for — it doesn't survive contact with strangers. It just lies there, intact, and is forgotten.
I've started thinking of writing as building the shape of a thing rather than the content of it. A doorway, a window, a chair. The song is the room. The listener brings the light.
What survives a song is whatever the listener carries out of it. Most of that is invisible to me. Sometimes a stranger tells me, and I am grateful, and a little embarrassed, because they have understood what I made better than I do. That's how the work knows it's finished. Not when you stop changing it. When it changes someone else.