Classical pieces in a number of movements - what in general connects them?

Question

It is well-known and traditional that symphonies, concertos, sonatas, and so on, consist (in general) of multiple movements. The styles and tempos of each of these is often conventional, for example starting with a dramatic and impassioned first movement, with a slow movement in the middle, and finishing with a bombastic finale.

But apart from adhering to the above structure (and a lot of the time such compositions actually don't), and apart from the fact that they are often in the same key (although not necessarily so), it is vanishingly rare for there to be a common musical theme running all the way through each of the movements. In fact, beyond the fact that they are intended to be played as a single suite, and hence heard all as a single suite, there appears to be no direct musical connection to the movements at all.

In my formal music classes at school, no insight was given into the analytical structure of, for example, a typical symphony, beyond the above observation of the fact that the movements are grouped together. I have explored my way through a fairly wide selection of the classical legacy: symphonies, concertos and sonatas, from Bach and Haydn to Shostakovich and Brian, and I have never been able properly to identify a "unifying" theme through any -- apart from some operas and ballets and more obviously programmatic music (e.g. Prokofiev's Romeo and Juliet; Walton's Belshazzar's Feast; Vaughan Williams's Job, etc.)

So: apart from the fact that they were intended to be grouped together by diktat of the composer, what does glue the movements of a symphony / sonata / concerto together?

Answer 1

There is no general way that composers use to link together the movements of a larger work. You could probably take corresponding movements of Mozart symphonies in similar keys and swap them around and it would still maker musical sense. Mostly the movements of a symphony stand in deliberate contrast to each other.

However there one particular method that composers often use to bind movements together: a musical idea (theme or melody) which is used one movement and then reused in a later movement. This is known as "cyclic form". This has been used since the Renaissance, went out of fashion for many years, and was then revived by composers of the Romantic era.
One good example is Gustav Mahler's first symphony. The first movement is in D major. Then the symphony goes through diverse other keys before the middle of the fourth movement where it returns triumphantly to D major and repeats a variation of the opening of the first movement.