Toccata and Fugue in D minor, BWV 538
The Toccata and Fugue in D minor, BWV 538, is an organ piece by Johann Sebastian Bach. Like the more well-known BWV 565, BWV 538 also bears the title Toccata and Fugue in D minor, although it is often referred to by the nickname Dorian - a reference to the fact that the piece is written with a key signature (zero flats) that is not normally used for the key of D minor, and would instead seem to indicate the Dorian mode.
However, the two pieces are quite different musically. Like the Fantasia and Fugue in C minor, BWV 562, it is nearly monothematic. It opens with a motoric, sixteenth-note motif that continues almost uninterrupted to the end of the piece, and includes unusually elaborate concertato effects. Bach even notates manual changes for the organist, an unusual practice in the day as well as in Bach's organ output.
The fugue, written in aeolian rather than dorian mode, is long and complex, and involves a rather archaic-sounding subject which prominently features syncopations and three upward leaps of a perfect fourth. The strict contrapuntal development is only broken in the final four bars, when a few massive chords bring the piece to an impressive close. The fugue of BWV 538 is very similar to the fugue of BWV 540. They both imply an alla breve time signature; they both use subjects with semibreves and syncopated minims, with a rhythm of constant quavers, rather than constant semi-quavers seen in most of Bach's fugues; they both use chromaticism, harmonic suspensions, and uninterrupted succession of subjects and answers.