Around 1742 Bach made a fair copy of a work comprising 14 movements. The work was then untitled, and it was not until 1747 that Bach formulated the title Die Kunst der Fuge [The Art of Fugue].
The governing idea of the work was an exploration in depth of the contrapuntal possibilities inherent in a single musical subject. The carefully constructed subject would generate many movements, each demonstrating one or more contrapuntal principles and each, therefore, resulting in a self-contained fugal form. Bach selected the key of D minor and crafted an easily identifiable subject with distinct melodic contours and a sharp rhythmic profile, whose regular and inverted versions, if sounding together in a contrapuntal relationship, resulted in flawless and attractive harmony, and whose chordal structure presented a pivotal cadential scheme.
In the course of the work, the main subject [theme] would be joined by various kinds of derived and freely invented counterpoints, would itself be gradually subjected to variation, and would also be combined with contrasting countersubjects.
[from Johann Sebastian Bach, The Learned Musician (Christoph Wolff)]
This late 1960's performance was by the Irish quartet, The Telemann Ensemble: Thérèse Timoney [violin], Lindsay Armstrong [cor anglais], Máire Larchet [viola], Aisling Drury-Byrne ['cello].