How sweet the sound

I like "Amazing Grace" very much. All the singer who songs this song has very beautiful and clear voice. When I hear this song, I feel myself relaxed. How sweet the sound!

I watch the documentary "Amazing Grace". I know this song is sung in various places. I find that the north place of America sing it but it is different from south place of America. I think this differnce stem from the number of black people. Black people sing it only their voice. On the other hand, white people sing it with musical instrument. I like the version without instrument.

According to the movie, the song was written by John Newton. But it isn't clear who made the music. He was a so-called black slave transport slaver trader. But When he experienced disaster, he got to believe God. So he decided to make songs for the atonement for sin.And he resigned a crew.

I think the song was made for not only himself but also every black people. John had some sort of regret. so this song is heard so sadly and holy.

(the lyrics)
Amazing Grace! How sweet the sound
That saved a wretch like me!
I once was lost, but now I'm found,
Was blind, but now I see. ←this show his regret, I think.

But I didn't understand all because speakers speak to fast for me.