I'm working on a solo program of all Debussy music. I've found Debussy difficult to memorize because he doesn't follow traditional chord patterns and progressions. He starts adding thirds to (most of) his chords, creating all sorts of cool washes of sounds and eliminating the traditional (Western) progression of primary and secondary chords. Memorization is tough. Adding all sorts of thirds makes it really hard to internalize just what the heck he's doing. Trying to read through his score, for me at least, is impossible (sigh).
I've found that by the time he's around a 11th, I've quit thinking in complex chord patterns. I just can't keep straight in my old brain that many notes stacked on top of each other. So I break it down to triads. For instance, a B-11 chord is basically a b-diminished triad combined with an a-minor triad. An example is the middle section of his first Arabesque (measure 39). And while he utilizes traditional chord progressions, he adds thirds to them, which de-emphasizes the traditional strength/sound of said progressions. I don't want to say he weakens the sound of the progression as much as he adds color as his emphasis rather than the chord progression itself. Again in the first Arabesque, he uses a tonic E-major broken chord pattern beneath what appears to be a tonic E-major descending chord pattern (measures 5-9), until one takes a closer look at the non-chord tones. What he has actually written is a C-sharp minor 11th chord above the tonic E-major triad. I guess you could argue all those extra right-hand notes are "just" non-chord tones, but I will argue that his use of triplet rhythm and the note pattern he uses takes away any sort of suspension/resolution around these non-chord tones. Rather, by using complex jazz-based chords, he achieves washes of color that become the primary sound effect. Chord progessions become subtle undercurrents of movement to create wonderfully unique Debussy creations.
All of which is well and good, and wonderful. Until I try to memorize the dang thing. Between trying to figure out chords he has composed, trying to identify actual chord progressions he is using, and trying to memorize chords that use all the letter names in the music alphabet (and then some), I can't decide whether it's my dyslexia that's getting in the way, whether it's Debussy's compositional style that's creating the problem....
... or whether it's just my old brain.
P.S. If you're interested in more of my take on Debussy's music and compositional genius, plan to attend my presentation at the Pikes Peak Music Teachers Association meeting on Tuesday, October 8, at 10 am, located at Graner Music on Barnes in Colorado Springs.