[kazinator]

> Maybe it’s time to listen to them again.

Elliott Carter would strongly disagree. :)

A lot of Baroque music is through-composed. For instance, the Prelude and Fugue forms that J. S. Bach composed some of his music in don't contain outright repetition, or not very much. Themes recur, of course, but in different settings: differently harmonized, in different keys and so on. The two-part form features repetition that may be omitted: while it's common to perform AABB, it can just be AAB, or AB. Sometimes there is a slightly alternative ending in B for when it is followed by A again. The Rondeau form has explicit repetition: AA BA CA ... XA.

[wizofaus]

Baroque music is often highly repetitive (even fugues are a form of material repetition!) - I would think there was a distinct trend from the 1600s to the mid 1900s where classical music became more and more through composed, until minimalism became suddenly popular.

[kazinator]

I think, you cannot have unity in a musical work if there is something new at every turn which does not reappear in any shape or form. In the best music from the Baroque era, there is new material throughout a piece. Many passages introduce motifs that do not make a reappearance. Or make a disguised reappearance just once.

I think, you will be hard-pressed to find two identical bars in a Bach fugue, where all the voices are doing exactly the same thing that was heard before. Even if a recurring theme appears, it's in a different way. Blatant copy and pasting is basically anti-fugue. Fugue-fail.

[wizofaus]

I'd agree it's rare to have exact repetition of a whole measure across all staves in a fugue, but you can certainly write a fugue using an initial theme and nothing but copy & paste with pitch shifting. Which you couldn't do for, say, a typical solo piano work by Scriabin or Messiaen...