BWV 565 has survived only through one single copy by Johannes Ringk (1717–1778), with the title Toccata con Fuga ex d. According to Dietrich Kilian,1 all other existing copies can be traced back to Ringk’s manuscript, directly or indirectly through an intermediate copy. We do not know if Ringk copied from a copy or from the original. A major debatable matter of the source is the incomplete measure 72. It comprises only three beats, four sixteenth notes are missing (Example 1).