Maybe an example or two would help.

Garth Brooks - "I've got friends in LOW places" has a happy marriage of lyrics and music since the word "LOW" goes DOWN in pitch. It would be very weird for it to go UP in pitch.

"Up, up and Away" (The Association?); the melody goes up, up and away.

Less specific, but maybe along the same lines: Happy-go-lucky lyrics are usually married to uptempo, major key songs.

It would not be good prosody, for example, to marry the lyric "I'm flyin' high on love today" with a minor key melody or a dirge tempo.

Conversely, the blues mostly have minor melodies ("blue notes") even if the chord progression contains major chords.


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Larry
www.audibleresponse.com