David Gordon Green fans ... HELP!!!!!

Ok David Gordon Green fans, I need your help here. I just finished watching Undertow this evening. It's definitely my least favorite Green film (still haven't seen Pineapple Express), but I absolutely loved the first half and don't regret watching it one bit.

Anyways, my question was a music question, and the reason I'm posting it here is because the Undertow board is just about dead and I figured I would get an answer faster here. Does anyone know the piece of music that plays for about three minutes during the scene when Jamie Bell's character makes the airplane for his brother's birthday and talks to his father as he's smoking a pipe? "Sometimes it's the strange things that stick with us the most". Love that quote. It is always the first song used in the film's theatrical trailer. I know Philip Glass composed the score, but it doesn't sound like his work and I listened to the film's soundtrack on Amazon and could not find this song. I NEED TO KNOW!!!! It's beautiful!!!

Thanks for your time.