Hexachordum Apollinis is a collection of keyboard music by Johann Pachelbel (1653-1706) published in 1699. It comprises six arias with variations, on original themes, and is generally regarded as one of the pinnacles of Pachelbel's oeuvre. The collection includes a preface in which Pachelbel dedicates the work to Dieterich Buxtehude and Ferdinand Tobias Richter and briefly discusses the nature of music.
The frontispiece, created by Cornelius Nicolaus Schurz, describes the collection as "six arias to be played on the organ, or the harpsichord, to whose simple melodies are added variations for the pleasure of Friends of the Muses. The instruments mentioned are referenced on the frontispiece: two cherubs are pictured, one playing a pipe organ (possibly with a pedalboard), the other a single-manual harpsichord or clavichord.
In Atttachments, you can download the musical score free.