Book excerpt: Roots of the Classical identifies and traces to their sources the patterns that make Western classical music unique, setting out the fundamental laws of melody and harmony, and sketching the development of tonality between the fifteenth and eighteenth centuries. The author then focuses on the years 1770-1910, treating the Western music of this period - folk, popular, and classical - as a single, organically developing, interconnected unit in which the popular idiom was constantly feeding into 'serious' music, showing how the same patterns underlay music of all kinds.