This might seem a rather dry way of talking about music, but I am trying to avoid that whole dichotomy between sterile analysis and vague metaphorical purple prose by talking about how we hear the structure and how the musical moods are created through it.
I'm afraid that this whole series of posts has and is going to have a very noticeable bias towards instrumental forms rather than vocal forms. There are several reasons for this. First, as I myself am an instrumentalist, not a singer, that is what I am most familiar with (even though I have done a huge amount of accompanying of singers and written a lot of songs myself); second, music with text necessarily involves a whole other level of complexity, but at the same time provides the listener with an obvious entry into the heart of the music, third; it is the very fact that instrumental music has no text, but "speaks" to us solely through the notes that is perhaps the biggest challenge for the listeners, so this is where the greatest need of discussion is. But still, I make my apologies to lieder and opera lovers for not taking them more into account. That might make an excellent series of future posts!
This post, like the last one, is about "long pieces with clear structural sections and easily identifiable themes." Perhaps the most successful and hence important musical form of all is the sonata form, which developed during the later 18th century and reached its highest point in the early 19th century. There are two sets of books on the sonata form, the first, three volumes by William S. Newman:
The Sonata in the Baroque Era
The Sonata in the Classic Era
The Sonata Since Beethoven
Soon after these three books were published Charles Rosen completely overshadowed them with these two absolutely brilliant books:
The Classical Style: Haydn, Mozart, Beethoven
Both these books cover how sonata form developed in the hands of Haydn, Mozart and Beethoven. Yes, there were many, many sonatas written in the Baroque era, but they were an entirely different kind of form than in the Classical era. The reason I am not going to talk about them here is that they were most commonly short pieces in binary form such as the hundreds of examples by Domenico Scarlatti. What happened in the Classical era is that, searching for new ways of writing instrumental music, they (meaning mostly Haydn!) invented a new kind of form, inspired, let it be said, by the techniques of opera buffa. Now for the first time, "pure instrumental music alone could be the principal attraction without the seductions of spectacle." [Rosen, Sonata Forms, p. 9] He goes on to say that:
The sonata forms made this possible by providing an equivalent for dramatic action, and by conferring on the contour of this action a clear definition. The sonata has an identifiable climax, a point of maximum tension to which the first part of the work leads and which is symmetrically resolved ... it has a dynamic closure analogous to the denouement of eighteenth-century drama, in which everything is resolved, all loose ends are tied up, and the work rounded off.Wow, so how the heck does instrumental music do this? The answer is, through harmony largely, though with contrasting themes to color the different harmonic areas and with a bubbling rhythmic structure to keep everything moving forward. The result is all those pieces that still make up the bulk of the classical repertoire: the string quartets and symphonies of Haydn, the piano sonatas and symphonies of Mozart and the piano sonatas, string quartets and symphonies of Beethoven. The first movement of nearly every one of these hundreds and hundreds of pieces are written in sonata form (sometimes called "first movement form" or "sonata allegro form" because first movements are usually allegro, a tempo word from Italian meaning "quick and lively").
Sonata form, as Rosen discusses in great detail, came out of a number of older binary forms. Typically, as developed by Classical composers, it still looked a bit like a binary form because it was in two parts, the first of which was repeated (though usually not the second). The opening of the first part, called the exposition, establishes the tempo, the key, characteristic thematic material (i.e. melody) and a texture. It also sets up a dichotomy between the tonic and dominant. Here is an absolutely characteristic example:
With Mozart, instead of just one simple theme (typical of Haydn) we get a whole cluster of themes. The key here is G major. But the crucial thing, for the 18th century, was the cadences and where they are placed. The first important one comes at the 46 second mark and is easily heard because of the rhythmic gesture and pause after. This cadence is on A, the dominant of the dominant, D. Then a contrasting section continues in D major confirmed with a full cadence in D at the 1:13 mark. This opening section ends with a cadence on D which sets us up for the repeat. The lilting charm of Mozart is conveyed in a couple of ways: the most obvious is the never-ending succession of winning and expressive themes. But equally important is the framework these are hung on, the harmonic structure which is organized by those cadences.
After the repeat, the second section begins (at the 3:12 mark) and in sonata form this is called the development because what happens in this section is what in a narrative drama we would call "the plot thickens". Instead of a major character experiencing some crisis, what happens in music is the harmony suffers a crisis! Sometimes there is a destabilizing shift to a remote key, but here, keeping things fairly simple Mozart first just repeats that opening theme, but now in the dominant. But then he subtly hints at E minor. Instead of continuing in E minor, he immediately picks up that repeated-note theme from the D major part of the exposition and uses it in a sequence moving around different key areas without settling on one. He keeps this up, hinting at different keys and using different thematic material from the exposition until finally, at the 3:49 mark he slips back into the opening almost before we realize it. The effect is a bit like a basketball player faking out the other players on his way to scoring a basket. This last section, called the recapitulation, will recall much of the material from the exposition, but the ending will be rewritten so as to end in the tonic, G, instead of the dominant, D. That is how the loose ends Rosen mentioned are tied up.
So that is one very brief walk through one example of sonata form. Yes, I know, this is only six minutes long, but I wanted to pick a simple example. What this kind of structure enabled was much, much longer movements that, by the time we get to Beethoven, can be fifteen minutes or more in length.