How does the brain work?

[asyncopated]

I'm writing this to try and understand better how music is learnt and welcome suggestions, comments and ideas. 

I've started learning to play the piano about a year back, and was fortunate enough to be able to read and understand some music already.  I've also the benefit of having listened to quite a bit of classical music, and this has help me to discern styles that I like.

Six months ago, I was looking through some Bach two part inventions (no. 13 and 14) and Schumann's Tramurai.  I remember these being pretty difficult for me to handle.  Since then I've not practiced those piece, but worked at something else: Mozart's Sonata Facile K545, (all movements) and some other pieces from the Kinderzenen -- Knight on a hobby horse and Foreign lands and people,  and also invention number 8. 

Just last night I was looking at Tramurai and both two part inventions (13 and 14) again, not having touched them during this period.  I can now roughly sight read through those pieces, and don't think I will be a problem learning them in short time.  I just don't remember these pieces being at all easy.  In fact, I thought that they were difficult!

So I'm wondering, what really has changed in the last six months? I.e. what exactly has my brain learnt, or understood -- such that even not having worked on these pieces, they have become so much easier?

al.

[kelly_kelly]

I think that what has happened in the past 6 months is that your brain has accumulated
more general musical knowledge and proficiency. Maybe your fingers have more stamina, or you have gained more ability to coordinate the two hands.  When you looked back at your old pieces, your brain applied this knowledge, making the pieces seem much simpler than it was before.

[Derek]

If you have been teaching yourself to sight-read properly, or happened upon an efficient process for reading on your own, these tend to be self-building and self reinforcing such that even listening to the piece strengthens the reading associations even when you are not reading. Fascinating thing, the human brain is.