Frederick the Great plays the flute with CPE Bach. Painting by Adolphe von Menzel

Respecting the intentions of composers is something we musicians strive to do. For guidance, students and historians of Historically Informed Performance are well served by several significant treatises on 18th century practice, technique and ornamentation, particularly those by Johann Joachim Quantz and Carl Philipp Emanuel Bach.

The two composers worked together for nearly 30 years in the Court of Frederick the Great and their opinion remains essential reading. As well as teaching how to play, their writings also instruct in what not to do – and they clearly express annoyance when directions are not respected.

For example, in Quantz’s On Playing the Flute (Berlin, 1752), the composer directed musicians to “improve, not disfigure” the music and stressed the importance of understanding the score:

“Almost no one who devotes himself to the study of music, particularly outside France, is content to perform only the essential graces; the majority feel moved to invent variations or extempore embellishments …”

“So many incorrect and awkward ideas appear that it would be better in many cases to play the melody as the composer has...