Phrase

Rhythm is a strong, regular, repeated pattern of movement or sound. In this case, the rhythmic repetition is happening at the opening theme. It's built upon the first 4 measures and the rhythmic repeption happens between the instrumentation. In the first two measures, winds play a downbeat, while the strings play an emphasized downbeat and add the rest of the quarter notes. The next two measures, both instrumentations play a similar figure of quarter notes and 8th notes. Those same 4 measures are repeated with a slight variation on the last bar, which serves as a transition into the next part of the opening theme. Strings go into a unison line that starts with a quarter note on the downbeat of that first part, then straight 8th notes for 5 measures. At the end of that phrase, there's a measure of quarter notes played by the strings, which sets up the new section and a modulation in the key.