The musical innovations within “Papa’s got a Brand New Bag” are announced with the opening fanfare and continue to emerge as the song unfolds. The first major change occurs on the first beat. The horn accents the one, leaving the sax and guitar to follow on the backbeat. Almost all previous forms of black music, including gospel, blues, and R&B, accented the two and four or backbeat.
Just about the time listeners come to terms with this innovation, they encounter another. A traditional chorus does not follow the first two verses. The closet thing to a chorus is an extended phrase or vamp where Brown rattles off various dance styles. The chords don’t change, and there’s only the tiniest of melodies before Brown returns to the chords and melody of the verses.
Having already denied any sort of structural predictability, Brown add a second, far more extended vamp filled by a sax solo. Again, there’s no chord progression; the rest of the band hovers on the same chord, serving only as a rhythmic backdrop for the sax. For more than 50 bars, the sax player, Maceo Parker, is free to go wherever he wants within this rhythmic pattern, as there are no chords or melodies limiting his movement.
Brown all but disappears for the last half of the song, only popping in periodically to provide additional rhythmic accents. He doesn’t really sing lyrics so much as use words like percussion instruments, and by the end of the song, Brown has joined the rest of the band as part of one large rhythm section.