Music
The simple theme begins slowly and quietly in the lowest registers of the orchestra, played first by the cellos, double basses and bassoons. After being recited, the main theme is then very slightly modified with a few different ascending notes, but transposed up a perfect fifth (to the key of F-sharp major, the dominant key, but with flattened sixth) and played on different instruments.
The two groups of instruments then move in and out of different octaves until eventually "colliding" with each other at the same pitch. The tempo gradually speeds up to a prestissimo finale, and the music itself becomes increasingly loud and frenetic.
Read more about this topic: In The Hall Of The Mountain King