Here's what the Wikipedia entry for this song (yeah, now songs have their own entries?!?!!): "When asked about the development of the song, during a track-by-track reveal, Martin said: "That's just about girls. It's weird that whatever else is on your mind, whether it's the downfall of global economics or terrible environmental troubles, the thing that always gets you most is when you fancy someone."
Sounds shallow, mate, but I'll give you the point.
To go back to the start. Tempting, eh? Possible? Maybe. Part of my healing process has included this kind of backward glancing: Before now there was the home I owned, and before that, a home rented, and before that our first apartment in Bryan. Keep going back to the start ... I was a student teacher, and before that an undergrad in College Station. Idaho comes next in this journey, or came first, and then I return to Minnesota, my first home.