Memorizing Songs Using Chord Numbers

I’m trying to memorize just the melody and root chords for “Body and Soul” by playing through all twelve keys. I’m using chord numbers instead of letters to do this. Here’s my question: The first three measures are ii7-V7/II-ii7-V7-Imaj-tritone sub V7/III. I think this is technically correct, but when I get to that last chord I have to quickly figure out the three chord, then the five of the three chord, then convert the whole thing into a tritone substitution. Three math problems are tough for my brain to do instantly. Would it be easier if I just write out the chord numbers as ii7-VI7-ii7-V7-Imaj-IV7 or is that cheating?

Hi @kirk2 , I’m happy you’re really thinking things through, working with scale degrees as you’re doing is the best thing to do! And even if it might feel slow and overwhelming at first, if you keep doing this, understanding harmony will get soon faster and more comprehensive.

My advice is to find the way it’s easiest to think FOR YOU. That said, I would say there is one thing that is always important to understand, even if you sometimes perceive the situation different.

The one thing is a V - I, dominant to tonic relation, and/or II V I. Remember II V is always one entity, it still functions as a dominant - tonic, have you the II in front of the V or not!

Another important thing is to always remember what you already know; when you have analyzed several songs, you start to realize that the same harmonic situations happen in all tunes. So when encountering a harmonic movement, first ask yourself whether you already know it!

Now, let’s take those first 3 bars of ‘Body And Soul’ you mentioned, just for a change in the key of C major:

Let’s go from the beginning:

Although you’re correct, the A7 IS VI7, I would think of it as a V (dominant) to the II D-7. This is because its dominant sound is “stronger” that it’s function as a VI degree. As this harmonic situation is very common, I would think of it as V OF II (dominant to the 2nd degree, just as you mentioned first). This can be found from songs such as:

Rhythm Changes Rhythm Changes: Form, Chords, Improvisation, Reharmonisation, PDF
Let’s Fall In Love
Actually any time you have a “turnaround” in a song.

Now, the trouble chord you mentioned. This is a good example where even as the F7 totally functions as a dominant to the E- (III), I would think the same way you did, IV7. This is just because that would make me think through the harmony faster, BUT STILL I would keep in mind that IT IS a dominant to the III!

I hope this helped,

Let me know if you have any further questions!