Johann Joachim Quantz was a German composer, flautist and flute maker of the late Baroque period. Much of his professional career was spent in the court of Frederick the Great, where he served as the king's flute teacher. Quantz composed hundreds of flute sonatas and concertos, and wrote On Playing the Flute, an influential treatise on flute performance. His works were known and appreciated by Bach, Haydn and Mozart.