I adore this song. It has begins with standard pop music and moderately thoughtful lyrics which is my favorite formula. Then, it moves into the about-to-run-off-the-rails section musically at the end that is another hallmark of great songs. Of course, actually devolving into utter musical chaos isn't allowed in great music. Any fool can be chaotic. It is in approaching the abyss but in not going over that is the mark of real work.
Lyrically, the song is true to its title. Then, as if it isn't any big revelation, the Muse steps up the lyrics 5 notches with the line:
"there'll come dreams, impossible not to do, impossible not to do."
The singer goes back to the song with some love song implication which tells me that the most important line is perhaps lost on her. Dreams that are impossible not to do? Chew on that while you enjoy this bit of existential brilliance.