Fortunately Florence has explained this song a little: "(...) like 'Heartlines' and 'Spectrum,' they're really earnest, saying don't be afraid of who you are and follow your heart. I get scared of being earnest. Like a lot of British people, I prefer sarcasm and irreverence. So those grand statements were hard for me. Wearing my heart on my sleeve. Very frightening." https://florenceandthemachine.fandom.com/wiki/Heartlines_(song)
Fortunately Florence has explained this song a little: "(...) like 'Heartlines' and 'Spectrum,' they're really earnest, saying don't be afraid of who you are and follow your heart. I get scared of being earnest. Like a lot of British people, I prefer sarcasm and irreverence. So those grand statements were hard for me. Wearing my heart on my sleeve. Very frightening." https://florenceandthemachine.fandom.com/wiki/Heartlines_(song)