With Body and Soul is a great bluegrass standard that is built around the b7** chord. What is a b7 you ask? A b7 is a major chord that is a whole step below the root chord of the song. In this case I'm playing the song in D major. The b7 is C major (and If we were playing a song in the key of A the b7 chord would be G major). This is because the song is in a fundamentally different tonality or mode called mixolydian.
A mixolydian scale is like a normal major scale, except that the 7th of the scale is flatted. So the notes of a D mixolydian scale are D(1) E(2) F#(3) G(4) A(5) B(6) C(b7). Notice too that these exact notes are the notes in a G major scale: G(1) A(2) B(3) C(4) D(5) E(6) F#(7). Another way to look at this is that D mixolydian is just a G major scale, but where you start and end the scale on D.
Regardless, none of this theory will make or break your ability to play this song, but it's fun stuff, and actually quite simple!
** That b is the flat symbol, btw, not a B note!
Topics and/or subjects covered in this lesson:
With Body and Soul
Loop 0:00 Run-Through of With Body and Soul
Loop 3:38 Breakdown of With Body and Soul
Loop 11:10 Closing Thoughts and Outro