The fourth poem is very playful. Nature, including birds, have to communicate the I-figure's lust and the brook must bring the mirror of his beloved.
The structure of the song is very simple, with three exact repetitions of the theme followed by a coda (m. 34-37). The piano accompaniment differs for the three parts of the song.
The song seems to start in Es, with plain Es octaves. The diminished chord before the Es chord at the last song also suggests a modulation towards another key than As. But the suggestion remains to be in Es, with only suggestions of Bes and As chords (without As!) on an Es organ point in m. 2-5, finally resolving into As at the start of m. 7. The right hand piano symbolizes flying birds, where it is an echo of the voice line that is build around a Bes chord. The long notes in the voice line of m. 3-7 is almost the same as the third motive of the first song.
The second half of the theme uses the same rhythmic pattern in a mainly downwards movement, and a continuous flow of 1/8 notes in the right hand piano. After a pause of the voice, filled in with a development in Es7 towards a full As chord at the start of m. 10 by the piano, an answer is given starting with syncope's in m. 10, where the piano pauses and then follows the line of the voice.
The first half of the second strophe is accompanied by a right-hand tremolo that may symbolizing the "Weste", where the left hand has just the echo of the voice line. The second half of the theme is accompanied by more or less the same bass line, but an octave higher, maybe suggesting the lighter atmosphere of words like "scherzend". The variations in the piano interlude in m. 23/24 are even smaller.
The first half of the third strophe shows downward movements in the right hand piano, suggesting the flowing of the brook, and the bass line has a countermovement with the voice line in m. 29-32, suggesting the mirror effect. On "fliess" in the text the piano continuous instead of the pause in the other verses, with a downwards movement, where the piano is an octave lower than in the other verses in the rest of the second half of the theme. In the coda the magic effect of the flowing back of the brook is reinforced by the repetition of the last part in increasing tempo, with a bass that has a continuous full chord 2/8-1/8 rhythm, and a modulation from As to G major, the fast change through the Fis in the second half of m. 36 going immediately into G major, perfectly representing the word "unverweilt".