The Classical Periods

Use them as rough signposts. Italy usually moved first and Germany followed decades later.

The decisive change is that people started writing chant down, and then stacking it.

Still in use: open fifths without a third sound hollow, which is why power chords work in rock and why film composers reach for them for anything ancient. A drone under everything runs from organum straight into ambient pads.

The correction: medieval music was not all monophonic chant. Dance and secular music existed in quantity across those nine hundred years, and monasteries were simply the only places with the means to write anything down.

Two things happened at once and they are connected.

Still in use: almost all pop, rock, gospel and soul is built on stacked thirds, which is a fifteenth century decision nobody ever reversed. Word painting, where the melody falls because the lyric is about falling, is five hundred years old.

The change around 1600 is one of the few real breaks, and it was ideological. Florentine intellectuals decided that complicated polyphony made the text unintelligible, and that music should carry the emotion of speech. Their answer was monody: one voice with an accompaniment underneath it.

Still in use: the lead sheet is figured bass with different symbols, and the repeating bass figure of a chaconne is the ancestor of the vamp and the loop. Every time a pre-chorus builds tension and the chorus lands, that is baroque logic.

The correction: Bach did not close the baroque. The date 1750 is administrative. The lighter galant style was already rising in the 1720s, Bach was seen as old-fashioned in his last decades, and his own sons wrote in the new language while he was alive.

Look only at the texture and the classical style seems simpler than the baroque: fewer voices, melody with accompaniment. That misreads where the complexity went, because it moved from the texture into time.

Still in use: the eight-bar period is the skeleton of almost all pop, and the last-chorus key change does in miniature what a sonata does at scale.

The correction: the term sonata form did not exist in the eighteenth century. It turns up in nineteenth century theory books. These composers worked with conventions about key movement and cadence placement, not with a scheme to fill in.

The romantics did not reject the classical system. They stretched it until it nearly broke.

Still in use: the late romantic orchestra with leitmotifs and chromatic build is the basis of the Hollywood score, carried to California by European composers in the 1930s. A chord shift up or down a major third with no functional justification is the standard sound for wonder in film and games. See film music.

The main change is that there is no shared language any more. A composer after 1910 picks their own material, sometimes per piece. Roughly four responses to stretched tonality:

Later in the century the recording itself becomes the composition. Pierre Schaeffer broadcast his first studies made from recorded sound on 5 October 1948, and Cologne opened the first electronic music studio in October 1951. Minimalism followed, with Terry Riley's "In C" premiered on 4 November 1964. See A History of Electronic Music.

The correction: the twentieth century was not atonal. By far the most music written, recorded and heard in it was plainly tonal: jazz, blues, pop, rock, musicals, film music, folk, and much concert music too. Atonality and serialism were influential in academic circles, especially in Europe after 1945, and were never the mainstream.

Think in devices, because all of them are available at the same time.

The real endpoint of this history is a toolbox with everything in it at once, where the question is not which era you are imitating but which effect you need. A power chord, a functional cadence, a key change into the last chorus and a static color field can sit in one track, and they come from four different centuries.