"Mixolydian". Yes, I apologize, I was typing in a rush to get out of the house and over to see a friend in the hospital. My mind was elsewhere.
Shostakovich makes an interesting -- and I'm afraid for your case, rather damning - example against the idea that we can intuitively know what emotion is intended, since he seems to have 'hidden' the 'true' intentions of many of his pieces after his tribulations at the hands of nasty apparatchiks like Zhdanov.
Personally, I prefer his quartets to his large-scale works.
So do I. The quartets are largely unhindered by the Socialists' needs. And I enjoy his jazz and movie soundtracks. Though his symphonies are intriguing for exactly what they do not say and for that which he would never say. However, keep in mind, you now have a prologue that has been fed to you by other interpreters of his music. Has your response to, say, the Fifth Sym. changed once you've read what "authorities" believe was Shostakovich's intent? Do you suppose Stalin had that same advantage? You are seeing this only from your own perspective sixty years removed and assuming this is what everyone heard on the premiere night.
Musicologists and reviewers have put words in Shostakovich's mouth without his consent. I believe the work you are reading will tell you more about his politics than most have thought of Shostakovich the man from his public statements or what had been published in the Western press after the war. If I remember correctly, his son has said his father always had a strong belief in Socialist politics and did his work to faithfully portray the society - and not necessarily the politicians - as worthy of praise. The deception Western writers have pinned on Shostakvich has largely, according to recent accounts, been a work of fiction produced to suit a Western audience, an audience who needed the Boogieman of Stalin vs. the everyman of Dimitri to keep them in their place after the war.
No, I don't think this is "damning" to my argument. It is indeed a very good example and one I chose intentionally being familiar with the tightrope Shostakovich walked throughout most of his career. The Western press used Shostakovich for their own intentions just as much as did the Socialists. I think using it as an example shows just how effective the emotions placed within the text actually are.
So we have a common interest. Why not drop the attitude and we discuss something that is far more interesting than DBT's?
If you play music then you should understand the construction of music. If that's the case, I don't see how you could say emotion is not in the music. I see it as absolutely within the text of the music, it's there before a musician even sees the first note. It is the building material of music. If it were not, what would music be? A series of twelve notes that we would quickly be bored with. No, it is the emotion set within those building blocks; the twelve bar progression with a turnaround, the heart thumping "feel" of a boogie, the naked rawness of heavy metal's power chords or the restatement and modification of a clasical theme that keeps us coming back for more.
It is as much in the text of the music as the emotions are in the words of a work of literature or theatre.
If we take three literary works; "Helter Skelter", "Alice's Adventures in Wonderland" and "Five People You Meet in Heaven", we find emotion just in those titles. Aren't we already aware of what we are likely to find in each book? The words themself tell us what emotions are likely to be encouraged by the author.
The same applies to music. If we are competent as players, we have learned to think of music as words, words then become sentences and sentences become paragraphs. This is how we make sense of the same twelve notes laid out in sometimes very similar fashion. A shuffle is a shuffle and it will always elicit the same response, only the time and key signature change. Just as with a paragraph in a book or speech within a play the construction of the notes into phrases alerts us to the emotions we are going to experience. If the time signature is 3/4, we know what to expect. If the time is set at 6/8, the response of the listener is going to be different just as the response is different when reading "Helter Skelter" and "Alice".
Anyway, what emotion or emotions is Bach aiming for in the first of the Two-Part Inventions?
What you are asking is, "What does the house look like that Bach has built with this work?" That's a little different than asking, "What building materials did Bach use to build this house?" What I am saying is when we look at the building blocks of the work, they are the parts that contain the emotions within each phrase of the work. If a composer selects a major key and a 4/4 time signature, we have an idea we will feel happy or at least content with those ideas at work. If the musicians play it as a 2/2, we know we will feel a sense of urgency. Largo and Presto will provide a different feel to the music as will pianissimo and forte. We might be fooled by a minor or blues pentatonic being played over that major chord progression but that is what makes the entire work different than its individual building blocks. We can place an extra door in the facade of the building and change the overall response to the entire work but the door remains a door and is always used as a door.
When you ask what emotion is Bach trying to communicate, you are asking about something more than I am discussing. What you are asking about is far more open to interpretation than a 7th chord in a I-IV-V progression. Just as two people might take away different impressions of the entire work by Carroll so too might two people come away with different impressions of Bach's individual works. However, if Bach or Lieber and Stoller did not understand how to use the building blocks at their disposal, there would be no telling one from the other just as there would be no distinction between "Alice" and Bugliosi's work or from the maudlin Albom novel if words did not contain emotions.
Therefore, we can like or dislike the entire work, respond this way or that to the entire work, but we respond similarly to the building materials. The flatted fifth of a blues scale will always be a flatted fifth and we will always respond to it with the same emotions. If we intentionally move the root to another note to play in a different mode, then we can expect another emotion to surface, dark and mysterious or exotic and unusual. It is the composer and the musicians who choose what building materials to use and they understand how we will respond to their efforts or else they wouldn't choose them. Our emotions are subjective - not objective as claimed - and one work might remind me of a specific event in my life while your emotions will be stimulated in another way. The Socialist dictator might be fooled into thinking the entire work was meant to praise his power but the individual phrasing of the work's inner core will provide the same emotional response from virtually everyone. The building blocks of key and time, pacing and scale will lead us all along the same path, it is only our subjective emotions, our own ego, that will land us at different locations.
Therefore, the emotions are in the text of the music. How we interpret them is subjective but the sign posts are the same. Whether we speed up or slow down when we see the "Yield" sign is open to our own interpretation. The author of that sign can only hope the intended emotion prevails.