What does it mean when a piece of music is thematic. For example a lot of Bach's lines of music are thematic - but what does this mean?!
I hope you can help.
Zoe =]

Ack. This is one of those awkward questions like "What does 'texture' mean in music?".

If you knew what a musical theme was I guess you wouldn't be asking the question. A theme is generally a phrase or two, which is melodic, and often recurs throughout the music. Its usually the part that gets stuck in your head, if you remember anything about a classical work. It can also be a unifying factor (structurally) in the music.

It really depends on the context that the word is used in, but that gives you some idea of what it means. In Bach's music the themes are generally fairly prominent, and can be used in different voices like in a fugue.

So saying that some music is thematic would be differentiating it from being motivic. Motives are generally only a few notes, whereas themes are complete phrases (longer).

Think of the Fugue in c minor from the Well Tempered Clavier first book. The first 5 notes would be a motive, and the first 20 notes would be considered a theme.