The second point that musicologists have disputed about the first movement is the existence of two expositions. The symphony begins with soft calls in the horns, the first horn playing what becomes the main material of the A-group while the others play long notes below. The music has its own rhythmic character ("long-short-short-long") and is centred on the interval of the perfect fourth. This first theme continues in the horns and bassoons while increasingly the music is developed by the woodwinds playing sixteenth-notes in parallel third motion until the second theme is presented and eventually takes over in measure 9. It is agreed that the B-group begins by measure 18. At this point a third theme is heard in the woodwinds – like the first theme also built on the perfect fourth but this time with the defining rhythm "short-long-short" – with tremolo accompaniment in the strings. At measure 28, the fourth theme enters still in G major and distinguished by its duple (equal) subdivision of the beat in the horns and woodwinds as a chorale-like chord progression. This exposition concludes with the return of the third theme, now rhythmically in diminution and melodically circular, fading away to an afterthought.