"Variously called rebop, bebop, or simply bop, the new approach was forged by restlessly innovative musicians who had grown dissatisfied with big-band swing, a dance-oriented style that required a predictable rhythmic groove, a sonic blend that favored tight section playing over improvised soloing, and an atmosphere of unfettered joy and gleaming optimism. Heralded as “modern jazz,” the new music favored small combos playing an opening melodic theme (the “head”) that introduced a set of chords, followed by a succession of solos in which players improvised new versions of the theme with agile, quicksilver runs through the governing chord progression, free to enrich the harmonic texture with substitute and extended chords. The tunes were played at blistering tempos. Drummers accented the soloists’ fractured, serpentine phrasings with abstract, almost ironic, snare drum riffs and—in place of the martial four-to-the-floor style of swing drumming—the deft dropping of bass drum “bombs” in odd corners of the meter. Freed from an obligation to accommodate dancers, these musicians now emphasized technical virtuosity and creative ingenuity. Modern jazz was a listening music, and many of its players insisted on being seen as artists rather than as entertainers."