I see this song as having a double meaning. I think it refers to both life and death. In the life perspective, it's talking about the struggles and stress of life wearing the mind down until there isn't much left. In the death perspective, it's asking if death truly is the end. Not even necessarily in an afterlife kind of way, but like just having something left of you when you die. This paradoxical duality of life and death in this song is why it's one of my favs.