What Brown wanted to do was lay down a strutting, macho anthem marked by explosions of brass and a guitar that sounds like chrome wheels spinning. He hums a melody to the sax player and a bass line to the bassist. He thumps out a beat for the drummer. He watches a trumpet player struggle, fires him, then re-hires him moments later. And when the singer is ready, he screams out a set of lyrics scratched on a sheet of paper. The song is called “Papa’s Got a Brand New Bag.”