Realizing what you know

Even as a little kid, I knew

The blues progression (I, IV I, V IV I).

The so-called "50s" progression. (I, vi, ii, V) ("Heart and Soul")

With that one, I also absorbed the ii V I itself.

The Andalusian progression of I, flatted seven, flatted six, and V. ("Hit the Road Jack")

I knew that a lot songs were just I, IV, and V, in various combinations, and that you ended on the tonic, that if you played any triad with only white notes you could just improvise freely using white note melody notes as well, or do the same in any other set of notes from any other major scale. I knew what AABA form was, or ABAB. These are not complex structures to understand.

So when I started to write songs at age 55 I was basically putting together things I had known my whole life. I threw in a few recently acquired chords and substitutions, and just added ninths to everything in a facile and amateur way to make it sound sophisticated. My first songs all had the same progression, going ii, V, iii, iv, ii, V, I, with minor variations. For some reason I liked to have the subdominant be minor chord rather than a major, and to use the tritone substitution for V freely, and to substitute iii for I.

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Not realizing what you already know can be an obstacle. Maybe you really don't know much, in which case it will hard for you to be a scholar, but you might know more that you think.