The song is about the passing of Rory (the singers) dad last year. He wants Heaven and earth to "collide" so he can see him again. These types of songs are always a hard listen to, when it's about someone who's passed on, especially a family member
If you like something a little heavier, check out their older music. My personal favorite is the burning of bridges by them. Perfect mix of heavy and his beautiful cleans. Such a phenomenal band.
