Iris is sort of a sad and happy song in a way.
It should be mentioned the reason for the title of Iris. Many people mistakenly believe the song was named Iris either because that was his love's name or because he sees her and the Iris is the beautiful colorful part of the eye.
However, the meaning behind the title Iris is more mythological in origin. Iris was the messenger of the Gods through the use of a rainbow (which is how the Iris in the eye got it's name). The rainbow united Heaven and Earth along which the God Iris would communicate with man from the Gods. The man in the song is so in love with this woman that he sees her as a Goddess, hence the line "You're the closest to heaven that I'll ever be." When he says "Cause I know that you feel me somehow" he is referring to the God Iris bringing his message of love to Heaven on the rainbow so that she will know.
