The descending organ notes of the Toccata and Fugue in D minor, BWV 565, are the universal shorthand for haunted houses and mad scientists, and everyone knows Johann Sebastian Bach wrote them. Except the sole surviving source is one undated, messy manuscript copied by a student named Johannes Ringk, and a decades-long scholarly debate asks whether the piece was written for the organ at all, or by Bach at all.

This episode walks through the manuscript’s oddities, including the soprano clef, a missing key signature written in the old Dorian mode, and Italian tempo markings unusual for a German composer, then deconstructs the toccata, four-voice fugue, and recitativo coda. It follows the piece from obscurity to Mendelssohn’s 1833 publication, Busoni’s piano transcriptions, Stokowski’s orchestration for Disney’s Fantasia, and Ennio Morricone’s church shootout, before examining Peter Williams’s 1981 challenge and the theory that the organ version is a transcription of a lost solo violin original.

• Why a bootleg-cassette-quality manuscript is all that stands between us and losing the piece
• Parallel octaves, a subdominant fugue answer, and harmonies too primitive for mature Bach
• The C sharp problem: an opening note early organs in Bach’s region often could not play
• What algorithmic musicology found when the score was compared with thousands of Baroque works
• Quadruple stops and bow-shaped arpeggios that point to a violin, or possibly a harpsichord