This is certainly an unusual prelude – 136 bars (over four minutes) of what is essentially an E flat major chord! It is part of Wagner’s operatic Ring Cycle, and this particular prelude is intended to convey the motion of the river Rhine.
It begins with a very long sustained tonic note in the bass instruments, with the dominant note being added in after four bars. Then we hear a sequence of intervals all played in the same rhythm (quaver upbeat on the first note):
This series is repeated several times, and then the different parts start to play them in combination with each other. The music has a serene feeling, particularly with the continued sustained tonic note in the bass. After a while the strings start to play a running melody based on arpeggios of the Eb chord, and for the first time we hear other notes in the scale (II, IV and VII), but always with the phrases leading towards the main triad notes. The texture builds up in the woodwind parts, and the strings switch from quavers into semiquavers, creating a feeling of movement. The prelude ends with a climax created from a series of ascending scales and crescendos.