Sad!
What I think when I listen to this is a little boy in a lone room. Nothing except a bed and a few little toys, He stares out the window and he sees his mother in the sky, She says keep strong my little child (something like that) the child get up and smile's but then he see's her disappear. He starts to cry and the music slows down and slowly darkens out.
Well this is very sad. But great song I really like it :D