Conversation so far:
Where did Pierre Boulez begin Pierre Boulez's musical education in 1943?
Paris Conservatoire.
What was his primary focus?
advanced piano.
Did he write any pieces during that time?
CANNOTANSWER.
Did he receive any special recognition as a student?
In June 1945 he was one of four Conservatoire students awarded premier prix, the only member of Messiaen's class to achieve this distinction.
What did he do after winning that award?
He was so infuriated by what he described as her "lack of imagination" that he boycotted the class.

Question: Who had what he felt was a lack of imagination?
Self-contained rewrite: Who had what Pierre Boulez felt was a lack of imagination?