For many centuries the pipe organ was the most complicated mechanical device known, as it took the artistry and craftsmanship of many different disciplines to construct one. Master cabinet makers to make the chests, keyboards and all the wooden parts, wood carvers to beautify the outside of the instrument, craftsman working in metals to make all of the pins and guide wires necessary, experienced makers to make hundreds and sometimes thousands of organ pipes, craftsmen with a fine ear to tune the pipes, organ players to assist with regulation of the action. All of this craftsmanship and knowledge was learned by experience by each organ builder in each part of Europe that they worked. There developed styles of construction and sounds according to the locality of the builder. Each part of Europe created their own unique version of the instrument, and accordingly there developed schools of organ playing to match the instruments of the locale.
The school of French organ playing began in the 16th century and unlike some others, continued into the Romantic era. With composer/organists like Camille Saint-Saens, Cesar Franck and Charles-Marie Widor, French organ builders went on to include improvements to the instrument that allowed the French organ composers to write in a symphonic style for the instrument.
The most influential and beloved of these composer/organists was Cesar Franck. After his early years of composing and performing he settled into a life of teaching. It wasn't until his later years that he started to compose again, and in the matter of but a few years managed to compose a handful of masterpieces. He was a master improviser on the instrument, but only composed about a dozen pieces for it. nonetheless, he is regarded as the most important organ composer since J.S. Bach. High praise indeed, as it attests to the quality of his compositions.
Among those few pieces he wrote for organ (and the last three pieces he wrote before his death) are the Three Chorales For Organ. Franck was a composer that loved the traditional forms of music, but he made these forms his own by the way he used them. The second organ chorale is in B minor, and is in the form of a passacaglia and fugue, a passacaglia being a type of variation form in which the composition is based on a bass-ostinato which appears throughout the composition. Franck used a 16-bar bass theme:
In true passacaglia form, it isn't always confined to the bass part. This work bears an outward resemblance at least in form to Bach's Passacaglia and Fugue in C Minor, but as with other works by Franck, his music is distinctive and speaks with a voice all his own.