The symphony, as a rule, is a composition for orchestra made up of four parts, or movements, which are not only related to each other by a bond of sympathy established by the keys chosen but also by their emotional contents. Without this higher bond the unity of the work would be merely mechanical, like the unity accomplished by sameness of key in the old-fashioned suite. The bond of key-relationship, though no longer so obvious as once it was, is yet readily discovered by a musician; the spiritual bond is more elusive, and presents itself for recognition to the imagination and the feelings of the listener. Nevertheless, it is an element in every truly great symphony.
It is the first movement of a symphony which embodies the structural scheme called the “sonata form.” It has a triple division. In the first division the composer introduces the melodies which he has chosen to be the thematic material of the movement, and to fix the character of the entire work; he presents it for identification. The themes are two, and their exposition generally exemplifies the principle of key-relationship.
In the case of the best symphonists the principal and second subjects disclose a contrast, not violent but yet distinct, in mood or character. If the first is rhythmically energetic and assertive–masculine, let me say–the second will be more sedate, more gentle in utterance–feminine. After the two subjects have been introduced along with some subsidiary phrases and passages which the composer uses to bind them together and modulate from one key into another, the entire division is repeated.
The second division is now taken up. In it the composer exploits his learning and fancy in developing his thematic material. He is now entirely free to send it through long chains of keys, to vary the harmonies, rhythms, and instrumentation, to take a single pregnant motive and work it out with all the ingenuity he can muster. Technically this part is called the “free fantasia” in English, and the Durchfuhrung –“working out”– in German. I mention the terms because they sometimes occur in criticisms and analyses. It is in this division that the genius of a composer has fullest play, and there is no greater pleasure, no more delightful excitement, for the symphony-lover than to follow the luminous fancy of Beethoven through his free fantasias. The third division is devoted to a repetition, with modifications, of the first division and the addition of a close.
First part of Beethoven’s 3rd Symphony (Karajan):