It appears that this tune was written in the 70's by Leon Russell. Since then it has been covered by dozens of artists but my personal favorites would be Donny Hathaway and Gavin DeGraw's versions.
Below is a pretty amazing version with Ray Charles performing at Willie's 70th Birthday Party which coincidentally was one of his last performances before he died. The ending of this song grabs a hold and doesn't let go. Watch as Willie sheds a tear.
After a bit of searching I was able to find this video that got me started on how to be able play this master piece. Now to try and figure out how to sing this monster.
Here is my humble version.