Trevor repeated throughout the class that these exercises are "about the slur." In his words, "a slur is always a diminuendo except...sometimes." He urged players to take these variations very literally; to play them without extra added emotion, nuance and romantic interpretation. The benefit here is from the rigors of doing exactly what the music asks for and nothing more. His suggestion was to begin with exercise number two. I have notated talking points for all of the variations that he spent time on. There were some that were skipped during class.
In a nutshell, these exercises are all "curiously unmusical" but we apply these as dedicated exercises so that we can use the skills needed when they come up (usually in brief moments) in our repertoire. The following are some of my notes taken during the class:
#2: Never shorten the last note of a slur (in these exercises, not necessarily in context). Slurs should be played with great pains taken to clearly diminuendo, de-empasizing the second note of each slur, without shortening the second note. It is truly an exercise in control and patience but pays off in dividends for moments that this skill is needed in the repertoire.
#1: "It doesn't feel musical to do the slurs this way, but it's just an exercise." Do it.
#3: Careful not to shorten the final note of the slur.
#5-8: More of the same: care must be taken to literally diminuendo on the slurs.
#9: Light articulation. It's about rhythmic "style," not literal rhythm. Alter this rhythm slightly by over-exaggerating the closeness of each 32nd to each 16th.
How much of each of these exercises should we play? Trevor's answer was that basically about 7-8 lines of study in each will establish the "feeling of what it's about."
#11: "Think of the dots as espressivo." Play the dotted notes expressively, and separated from the rest but not very short.
#13: Basically, pretty darn difficult to truly give accent to the lower note but try your best to get it done.
#14/15: (For musicality), "fast notes (the 32nds) should go a little faster."
#16: The little note is crushed as close as possible to the next note. Really work at that.
#22/25: These are "not so important;" there are "better double and triple tonguing studies for that."
About tonguing forward: "The tongue should be closer to where the voice of the FLUTE is [ie, forward] to be clear...what sounds clear when speaking does so because it's closer to the [speaking] voice." He made reference here to how clear actual speech can sound when using the tongue further back due to the tongue's proximity to the source of our actual speech, the voice box, yet the source of our flute sound is where the air from the aperture meets the flute, so we must tongue closer to the source of the sound. Comparisons were also made to the innate suitability to great articulation that certain languages, such as French, provide the player.
#32: Some of these are "not so worth it."
#33: Really go for the correct amount of "trills."
#36: "There are better double tonguing studies in other books."
Re: actually performing the Allemande: "Messing around with it, you can do too much. Better to let the music speak for itself."
#42: Practice a great single tongue here, not triple.
#43-46: "I don't think it's worth practicing."
#48: "Very valuable!"
#49: "Waste of time."
Here, at this point, Trevor had both of the performers play all the way through the rhythmic tour-de-force of Number 50. After which he quipped: "Moyse said: 'never play this in public', " which elicited a lot of laughing in the audience.
In summary, the exercises are useful ways to focus very specifically on certain aspects of one's playing, most notably slurs, style, and articulation.