Bach wrote two sets of symphonies while in Hamburg. The first six were symphonies for string orchestra and were commissioned by Baron Gottfried van Swieten, Austria's ambassador to Berlin, who had traveled to Hamburg to visit Bach. Thanks to the patronage of van Swieten, Bach's music came to be performed in Vienna. It was at Sunday concerts given in van Swieten's home that Mozart heard works by C.P.E Bach as well as J.S. Bach and Handel.
The four symphonies in twelve obbligato parts shows Bach at his most inventive. The earlier style of his father's that saw a single mood dominate a composition is thrown overboard in these symphonies as the younger Bach throws mood changes as well as key changes, rhythmic changes, and sudden pauses at the listener in each one of these symphonies. But despite the surprises in them, Bach manages to keep a flow to the music that creates a sense of balance between form and spontaneity.
The Symphony In E-flat is in three movements:
I - Allegro di molto - The movement begins with the full orchestra followed by phrases filled with trills played by the strings that are separated by pauses. The full orchestra resumes playing with the violins playing phrases of repeated notes. The second subject is played by the flute with simple violin accompaniment. The development section begins straight away with no repeat of the exposition. The opening material returns, themes modulate and segue into the next movement that begins without pause.
II. - Larghetto - A gentle tune is played by the flute, then taken up by the oboes with string accompaniment in this very short movement.
III. - Allegretto - A rhythmic movement in sonata form that contrasts with the short preceding larghetto. The violins chatter away, the winds add their share of seasoning to the mix. The first section of the movement is repeated, and is followed by a development section. The opening section returns once more with modulations occurring in the themes.