The defining moment of Glenn Gould's career came in 1964 when, at the age of 31, he withdrew from all public performance. The move was viewed by audiences and critics as willful and bewildering, and was seen as evidence that despite his demonstrably supreme artistry he was, in the argot of the common man, a nut. 　　 　　But, as George Szell once said of him, "That nut [was] a genius." In his short international career, which spanned only 24 years, Glenn Gould changed the way the music world thought about performance practice, recording, and the music of Johann Sebastian Bach.