Conversation so far:
Where did Pierre Boulez begin his musical education in 1943?
In October 1943, he auditioned unsuccessfully for the advanced piano class at the Conservatoire, but he was admitted in January 1944 to the preparatory harmony class of Georges Dandelot.

Question: What was his primary focus?
Self-contained rewrite: What was Pierre Boulez's primary focus under Georges Dandelot?