Bach’s best-known organ piece is probably the best-known organ piece, full stop (no pun intended). Toccata and Fugue in D minor, BWV 565, is a youth work full of what he would later deprecate as “keyboard hussar” artifices. He himself appears to have disowned it later in life: the extant manuscript is a copy by a student (Ringk) of a student of Bach’s (Kellner).
It has been noted numerous times that the work contains many passages that are highly idiomatic on the violin, such as
bariolades [sp?] bariolages [thanks, Mrs. Arbel!]:
The subject of the four-voice fugue is made up entirely of sixteenth notes, with an implied pedal point set against a brief melodic subject that first falls, then rises. Such violinistic figures are frequently encountered in Baroque music and that of Bach, both as fugue subjects and as material in non-imitative pieces.Wikipedia
Such figures are indeed violinistic (and guitaristic!) if the pedal point is an open string: you can then alternate bowing viz picking between the open string and the notes you are fretting on the adjacent string. Bach was proficient on string instruments himself (albeit not a performing virtuoso, like he was on organ and keyboards), and indeed on numerous occasions transcribed violin works by himself and others for keyboard. (Indeed, it is not quite clear which was the chicken and which the egg in some cases, such as the organ fugue in D minor from BWV 539 and the fugue from the sonata for violin solo in G minor, BWV 1001.)
So there are arrangements for solo violin of “Toccata and Fugue”, almost universally transposed a fifth up to A minor so the piece will fit the instrument.
Then I thought: wait, if they were playing on viola instead (said much-maligned instrument being tuned a perfect fifth lower than the violin), they could do it in the original key?
At least two violists (viola players) on YouTube have done creditable jobs of it. The second one plays with a sense of rhythm I can only describe as “rocking”.
ADDENDUM: another unusual feature of the Toccata are the passages in parallel octaves — AFAIK unique in Bach’s organ work. Christoph Wolff explains though:
“…persistent octave doubling, for which there is no parallel elsewhere in Bach’s organ music. However, if we consider that Bach’s Arnstadt organ had no manualiter sixteen-foot stops available, the octave doubling reflects an ingenious solution for making up that deficiency and for creating the effect of an organo pleno [“full organ”] sound that typically requires a sixteen-foot basis.”Wolff, Christoph. Johann Sebastian Bach: The Learned Musician (Norton Paperback) (p. 72). W. W. Norton & Company. Kindle Edition.