In the late middle ages western harmony started on a journey that would take it in a completely separate direction to that of the music of other parts of the world. It discovered chords, and, over the next seven centuries, began to unlock their harmonic possibilities. In this film Howard looks at how western harmony works, and how, in the present day, it has fused with other forms of music to create new styles.Chords led to chord progressions, and Howard looks at how familiar patterns of chord progressions give all kinds of music from classical to popular their sense of forward movement. Why do the same chord patterns appear again and again, from Renaissance Italy to the latest chart hit?