Contrapuntus IX from 'The Art of Fugue' by Johann Sebastian Bach

Bach's 'The Art of Fugue' presents a 'treatise' on the form of fugue, the "form" actually being more of a process of composition. J. S. Bach is the undisputed master of this genre of imitative counterpoint. All 13 of the 'contrapuncti' of the set explore the imitative possibilities of a single fugue subject, or beginning "theme" in more modern parlance. This number IX in the set is for 4 voices, no instruments specified (here arranged as four parts spread through five instruments), and is a "double fugue" which means it has two subjects, and it contains invertible counterpoint, where the subject can be placed in any voice, high, middle, or low, and still fit in the tightly woven structure. This takes planning, and a mind that understands where the music will head and that it will work in its own strict confines of procedure. - Brass players have always found Bach's music to be very attractive literature for arranging. The instruments do well imitating the sound of Bach's own instrument of choice, the organ. Bach wrote masterpieces directly involving the brass as the trumpet part of his Brandenburg Concerto No. 2 can attest with its high brilliance and technical demands that throws down a gauntlet to each generation of trumpeters who dare to try and surmount it.
~ Steve D. Matchett, September 18, 2020