For 10 points, name this harpsichord collection consisting of an aria followed by thirty variations, published in 1741 by Johann Sebastian Bach.
David Humphreys suggested that a "Cosmic Allegory" unifies this work, while Alan Street claims that it was written in defense of criticisms made by Johannes Scheibe. Its twenty-fifth section contains many chromatics and was nicknamed the "Black Pearl" by the person who recorded it first, while Jozef Koffler created an orchestral transcription for this work in 1938. Every third section in this work is a canon except the last, which contains two folk songs as a quodlibet. Revived by Wanda Landowski, it helped bring success to its 1955 performer, Glenn Gould. For 10 points, name this harpsichord collection consisting of an aria followed by thirty variations, published in 1741 by Johann Sebastian Bach.
David Humphreys suggested that a "Cosmic Allegory" unifies this work, while Alan Street claims that it was written in defense of criticisms made by Johannes Scheibe.
the Goldberg Variations