Modal jazz is a development beginning in the later 1950s which takes the mode, or musical scale, as the basis of musical structure and improvisation. Previously, a solo was meant to fit into a given chord progression, but with modal jazz the soloist creates a melody using one or a small number of modes. The emphasis in this approach shifts from harmony to melody.[127] Pianist Mark Levine states: "Historically, this caused a seismic shift among jazz musicians, away from thinking vertically (the chord), and towards a more horizontal approach