It seems like the overall theme is regret and the bittersweetness of letting go of regret. But I think that like with many Thom Yorke/radiohead songs, the lyrics are vague enough that they could be about almost anything, but they are also so poignant and emotional that it makes you think of whatever has the most meaning to you. I think that when you hear it, this song is meant to bring out all the regret and bittersweet feelings you have in your own life, which can make you sad, but that's what makes it a great song. I love how mellow it is too, it conveys so much emotion in a way that is a subtle enough to match the emotions being conveyed.
It seems like the overall theme is regret and the bittersweetness of letting go of regret. But I think that like with many Thom Yorke/radiohead songs, the lyrics are vague enough that they could be about almost anything, but they are also so poignant and emotional that it makes you think of whatever has the most meaning to you. I think that when you hear it, this song is meant to bring out all the regret and bittersweet feelings you have in your own life, which can make you sad, but that's what makes it a great song. I love how mellow it is too, it conveys so much emotion in a way that is a subtle enough to match the emotions being conveyed.