"The psychological effect of all this key-shifting, some jerky, some smooth, is very difficult to describe...perhaps it is the magic of Bach that he can write pieces with this kind of structure which have such a natural grace to them that we are not aware of exactly what is happening." In this episode we use these words by author Douglas Hofstadter to explore Bach's harmony as a deep stack of entangled and recursive structures. A moment from listener Santiago is the smallest of these stacked units, and we use it to zoom out. 

French Suite no. 4 as played by harpsichordist Pierre Hantaï for the Netherlands Bach Society (the Allemande is first):

https://www.youtube.com/watch?v=J2rQtGtxpOw