Mozart Orchestration Question

I'm no longer what would be considered "young" by young people, nor am I a beginner at composition (which "young" could be taken to mean in translation) but I am relatively new to orchestration. Though I've taken courses, read many texts, and so on, there is no substitute for "learning from the masters" IMHO so I've been going back and doing what I should have done years ago, which is to study scores and see what composers did.

Now, I'm also a "modernist" so I don't compose in a "classical" style, so I know we've moved on from that. But for the sake of "learning a specific tradition", I wanted to tackle this.

So I'm looking at Mozart's very first Symphony, the score for which can be found here:

http://petrucci.mus.auth.gr/imglnks/usimg/b/b0/IMSLP00033-Mozart_-_Symphony_No_01_in_Eb_Major__K16.pdf

I'm curious why he made the choices he made. Now, granted, Mozart was EIGHT at the time of this composition. It's highly likely he just didn't know what he was doing yet :-) Of course, we can argue how much genius he had all day long but even with the god-like status we've ascribed to his early feats, it's still within the realm of possibility that he just didn't have the life experience to make "correct" choices here. But I do think his choices were at least deliberate, if not informed.

If I had this theme, I would have orchestrated the opening 3 measures just like he did - except I might have had the horns in unison. But, it's pretty logical to me.

Measure 4-11 is where the "logic" falls apart for me - or rather, I just can't see any.

No problem with the bass voice - it makes perfect sense and only the Celli/DB are doing it.

The Oboes also seem to be completely logical, playing the important notes of the 7-6 suspension figures (aside from the first G octave which is a little out of kilter).

And I know at this time the horns would be natural horns, so they had to play notes they could play, rather than any note you wanted them to. That's why they have Eb, F, and G, and Bb. Largely logical choices to me.

But the upper strings...

I mapped out the first 3 chords and I can't find very much logic in the choices being made.

They are "interlocked" in that one instrument from another group is in between the notes of any one group, but beyond that I can't see any rhyme or reason for the notes chosen.

Looking at the 4 part harmony, I do in fact see where some "proper voice leading" is taking place at least in the lower octave (where the bulk of the strings are). But other than that, the choices seem rather random to me.

It's funny for example, that on the first chord the G (lower note of the oboe octave) is so heavily weighted. The distribution becomes more even (2 parts on any one note) as it progesses but it's still - let's just say, not what I would do. I would do something "more consistent".

But I don't know that mine would come out "good" just because it's "consistent".

So, why?

P.S. I'm looking for serious answers from experienced individuals, not just "because he was Mozart" or things like that! I realize this isn't a well-travelled forum but I'm hoping there are at least some experienced orchestrators participating and people who are familiar with classical harmony, etc.

If I understand your question, the upper strings are playing double stops, so playing thirds and sixths are quite idiomatic.

If I understand your question, the upper strings are playing double stops, so playing thirds and sixths are quite idiomatic.

Actually today, it is common practice in orchestral playing to almost never play double stops. If you watch any proffesional orchestra, they will mostly divide everything unless specifically told to play double stops. This just improves intonation and ensemble. Also, playing the double stops is just unnesecary extra work. However, I'm not sure what the convention was in Mozart's time. He could have been assigning notes to the string instruments with double stops in mind because thirds and sixths are more likely to be in tune than fourths or fifths.

The one voice leading thing that stuck out to me as weird was the doubling of the 7th (Eb) in the 9th bar. And yeah the emphasis on the G in bar 4 seems quite strange. I also think the doubling the oboe suspension at the octave in the second violins is questionable. The voice crossings between the violins also looks muddy especially in the lower seconds from bars 5-6 where they have a tritone leap that isn't resolved at all. I don't know what the explanation for all this is though. We could attribute it to simple inexperience or thinking harmonically rather than contrapuntally. It's also possible that the extensive doubling of lines was done with rather poor orchestras in mind who needed help from the composer to sound fuller. I think you can attribute some of Schumann's "poor" orchestration to this as well.

Actually today, it is common practice in orchestral playing to almost never play double stops. 

Yeah, not really a fan of that practice. I mean in some cases it is a necessity to divisi, but in this example I would encourage players to play double stops. You also have to remember that orchestras in Mozart's days were a LOT smaller than ones today. I wouldn't be surprised if Mozart had only one or two players in mind for each string part, thus reinforcing some notes and not others.

Yeah, not really a fan of that practice. I mean in some cases it is a necessity to divisi, but in this example I would encourage players to play double stops. You also have to remember that orchestras in Mozart's days were a LOT smaller than ones today. I wouldn't be surprised if Mozart had only one or two players in mind for each string part, thus reinforcing some notes and not others.

Yeah, the practice may not be the best in terms of historically informed performance. However, it is very much a part of the present aesthetic that values a round beatiful sound at all times. Playing double stops presents several problems, the most important of which is that an instrument playing 2 notes at once will sound about twice as loud. This creates a nightmare for dynamic balancing, to say nothing of when people try to play 3 or 4 notes at once, which can often distort the rhythm and articulation.

Well, you all did well because I hadn't even considered the Divisi vs. Double Stops question. I assumed Divisi. I was noticing that there were no 5ths in the strings parts but one can argue that 6ths are more "sonorous" anyway. But there are a couple of 4ths in the Viola.

I hadn't thought of the possibility of Double Stops though - of course 5hts are much harder to play on strings, whereas 6ths (and to some degree 4ths) are much easier to finger.

So these choices, much like the restricted notes of the Horns, could be one of logisitcs.

What would now be interesting would be to go back to other scores and see if this holds true for his subsequent string parts - if it's a generality across the board...