I don't listen to much classical; however, I recently found this beautiful work by Chopin. I am wondering if you could help me explain a particularly amazing moment in the piece. Please refer to minute 26:00-26:10 for reference in the attached youtube clip. Below is an image of the section:
The first five (5) bars have a minor quality to them and sound quite hopeless. But then the sixth measure comes out of nowhere with that G-flat -> D-flat chord sequence that just feels like a breath of fresh air.
Could you explain this to me? My first guess would be that in the first 5 measures we are in the relative minor of the key and then move to a PAC in the relative major key, thus bringing the positivity. But the key with 4 flats is A-flat major (D-flat being the subdominant chord), so that doesn't really seem to be it. The G-flat -> D-flat change is a dominant-tonic one, but not in the current key. So were we modulating to D-flat major just for a moment?