What's a Musical Idea?

Years ago I took a course in musical cognition in the musicology department of the Hebrew University, and I was frustrated by the huge gap between the cognition that was the subject of the course and the cognition that interested and still interests me.
My interest in the subject was then related to my efforts to learn to improvise in jazz, and the course was concerned with the way the brain processes pitch and the other basic elements of music.
I'm still interested in musical cognition, in how a person thinks in the medium of music. I want to know how a concert pianist commits complex works to his or her memory, how a conductor learns a score and gets an orchestra to play it the way he or she wants it to be played, how a composer conceives of music before he or she writes it out, and how a jazz improviser invents a solo over the harmonies of a standard. The academic study of cognition is very far from explaining matters that complex.
In his popular lectures on music, Gil Shohat often speaks of something quite simple in a classical piano work, such as two descending notes, as a musical idea, which is repeated throughout the piece. While I see his point, and I cannot deny the presence of that feature in the piece, once he points it out to me, the descent from B to A, for example, seems much too simple to be called an idea.
Recently I have been trying to learn the first of Wilhelm Friedemann Bach's duets for two flutes, music that is so full of idea that it's hard to play and follow. I have been trying to give my practice meaning and direction by noticing his ideas and wondering just what I would call an idea if I were analyzing the piece.
Here's the first measure of the piece:

How many musical ideas do these ten notes convey? One idea is the rhythm, the division of the three beats of the measure into nine triplets. Another idea is the spelling out of the e minor triad on the first beat of the measure, telling the listener (and player) what the key is. A third idea is jumping down from the high 'e' to 'b' and then continuing down the scale rather than extending the initial arpeggio. Yet another idea, and an interesting one, is turning the last note in the measure, the low 'e,' which ought to be, as it were, the resolution of the movement, into a passing note and landing on "d#" at  the beginning of the next measure, which echoes the shape of the first measure:

Thus, that shape is also a musical idea.
It would be tedious to go on, as my point is to point out the complexity of both musical ideas and the task of identifying them. Bear in mind, that these two measures appear before the second flute joins in and adds an exponential element to the piece.
Playing W. F. Bach's music is an enriching experience. My purpose in looking for the musical ideas as I learn to play the piece is to play it more intelligently, and also to keep up my interest and avoid playing mechanically as I play the piece over and over again in my effort to master it.

My Solo and Benjamin Goodman's

On Friday morning, May 31, 2019, I stood up with my massive baritone saxophone dangling from a strap around my neck and played a song the Muppets made famous, “Ma Nah Ma Nah,” backed by the (very) amateur wind orchestra where I play every Tuesday night. Usually the baritone saxophone has a rather modest (though important) role in the pieces we play (things like songs from “West Side Story” and “The Pirates of the Caribbean”). It accompanies the rest of the orchestra, from the bottom, along with the other low instruments: tuba, trombone, and baritone horn. So, getting a chance to solo in front of the band was an unusual challenge and opportunity. I’m grateful to our young and energetic conductor, Yonatan Leneman, for asking me to do it.

My solo was not terrifically demanding, but it was jazzy and fun. I practiced very regularly and consistently, probably more than I had to, to get it right, and I was almost satisfied with the way I played. The venue was outdoors in the courtyard of the new state religious elementary school in the Israeli city of Mevaseret Zion, and the audience consisted of the pupils, their parents, and their grandparents. Before playing, I told the audience that I spent my first months in Israel in the Absorption Center at Mevaser Zion, in 1973, long before the city was developed intensively.

I took the assignment as seriously as though I were going to be on stage at the Jerusalem Theater, though I can’t say I was nervous. Excited, yes. And confident.

The night before my solo, we hosted a piano recital in our home by a young and extremely accomplished pianist, originally from England: Benjamin Goodman. He played an ambitious and difficult program, including works by Bach, Debussy, Liszt, and Schumann, for an intimate audience, mainly our friends. It was a thrilling performance. Benjamin has fantastic technique and plays communicatively with deep understanding. He spoke briefly, modestly, and informatively about the pieces before he played them, with his fine Oxford accent (“Waltz” came out “Woots”).

The difference between the high level of Benjamin’s playing and the profundity of the music he played puts my solo on “Ma Nah Ma Nah” in an ironic light, though I’m proud of myself for performing creditably.

I have a childhood prejudice for classical music. I was brought up to respect and appreciate it. My mother used to take me to Saturday matinee concerts at Carnegie Hall. I was taught classical piano for a few years, till I knew I was going nowhere with it. When I took up clarinet, the orientation was definitely classical, and I never rebelled. I love jazz and listen to it often. I admire the skill and musicality of jazz musicians. I heard a lot of folk music when I was growing up in Greenwich Village and attending a leftist school, where, when we were required by law to have a nuclear air raid drill (as if anything would have protected us if the Russians had bombed New York), we gathered in the basement of the school and sang peace songs. Since moving to Israel, I have also listened to a lot of Middle Eastern music and enjoy it. The skill of our players like Yair Dalal and Taiseer Elias thrills me. Nevertheless, at bottom, I prefer hearing Western classical chamber works (symphonies often are too bombastic for me – I have tried and failed to enjoy Mahler).

When I took up flute, I had a phone conversation with my prospective teacher and told him I was interested in playing baroque music. But right afterward I said I wasn’t interested only in baroque music. I wanted to master the instrument (I am getting closer, after more years than it would have taken a gifted high school student – indeed, more years than it took me to get to a higher level on clarinet when I was in high school). My idea was that I wanted to be able to play well enough to read duets with friends, not to perform. Though I did work on a piece by Schumann with a pianist and perform it for a home audience, at the end of the recital he gave at our house.

Now I’m working on flute duets by Wilhelm Friedemann Bach, complex and demanding music. I’ve been practicing the first one for a couple of weeks now and am still nowhere near to mastering it enough to imagine performing it. In fact, I doubt I’ll ever get there. I play it with my teacher in my lessons, and that’s about as public as it’s going to get. The pleasure of playing with him is elevating. And the effort to learn a piece well, and then to learn another one and another one, increases my respect for Benjamin Goodman infinitely.