There is a point of view that all the western music is divided by Bach. The before era when music is mostly based on intuition and imitation, and the after era when music is strongly based on elementary theory. Bach himself, interestingly, belongs to the "before" era and as such is a pinnacle of intuitive pre-elementary music.

Just yesterday I found an album of Elizabethian remakes of Nick Drake's songs mixed with John Dowland's. The difference in composition is staggering. And Nick Drake was not a typical songwriter himself. Yet a 50 years old song is principally different from a 500 years old even when played by the same people on the same instruments.