Bach was hired in 1708 by the ruling duke of Saxe-Weimar, Wilhelm Ernst, as an organist and member of the court orchestra; he was particularly encouraged to make use of his unique talents with the organ.^[3] During his tenure at Weimar his fame as an organist grew, and many students of the organ visited him to hear him play and to learn from his technique.^[4] The composer also wrote many of his greatest organ works during the period, including the Toccata and Fugue in D minor, BWV 565 and the Prelude and Fugue in E major, BWV 566.^[5] The Fantasia and Fugue in C minor was begun during this period, as a lone fantasia in the title key. The fugue was added in 1745, most likely by Bach, but possibly by one of his students or sons. This piece is one of a few by Bach with a considerable period between the composition of its component sections.^[1]

The whole piece lasts about six minutes,^[2] and comprises an 81-bar fantasia and an unfinished fugue, of which 27 bars are written. The fantasia has a very imposing structure and sound, the feel of which is created by the piece's one-measure generative theme. This theme passes between five contrapuntal voices of the organ, with occasional movement into new ideas; even the pedal bass is used for the theme. The theme contains many appoggiaturas, which provide the piece with a slight virtuosic feel. The fugue is written in ⁶
₄ time and uses a simple half–quarter rhythm. It ends abruptly in the middle of the 27th bar after the exposition of the five voices is completed and a stretto passage begins.^[1]

• Fantasia and Fugue in C minor, BWV 562: Scores at the International Music Score Library Project
• Free download of BWV 562 recorded by James Kibbie on the 1724-30 Trost organ in the Stadtkirche, Waltershausen, Germany