Mercury whirls around the orchestra in scurrying figurations. It is in three balanced parts ABA.
Theme A: There is no clear theme heard, but wisps of notes which dart about unpredictably from section to section in the orchestra. Much dovetailing of instruments across registers. There is use of bitonality and arpeggio in the accompanying figures, which adds to the sense of movement.
Theme B: is an amazing succession of eleven repetitions of a Theme which is kaleidoscopically scored.
This is the quickest and the shortest movement of the suite. Aside from its speed, however, its particular quality comes from the opposition of two simultaneous keys and two simultaneous rhythms. The two keys, which are sounded in the very first bar, are B-flat and E (which, being separated from one another by the interval of the tritone, have no note in common).
The two rhythms arise out of different groupings of six beats, the first being ONE-two-three-FOUR-five-six, the second being ONE-two-THREE-four-FIVE-six. This opposition of contrasting patterns is one of Holst's principal characteristics, and other examples of it can be found in The Planets.