These two works are arguably the capstone of all of Bach's works.
The Art of Fugue encapsulates everything that he wanted to say about the science (and indeed mathematics) of the creation of musical forms. The work is rigidly structured, yet diverse; it's studious, yet an entertainment. This version (there exist quite a number) is in 22 "movements", each of which has its own taxonomic classification, all of which are based around a simple yet compelling theme. Variations on that theme include turning it upside down, playing backwards and inside out (I exaggerate minimally) and pitting it against itself in several voices. And as a work of entertainment, it works as well as it does as a scholarly treatise.
Apocryphal tales abound concerning the fact that he hid his name (the legendary 4 notes B-A-C-H) in the final movement, and at that moment breathed his last. The truth is more mundane than that, but the fact remains that this is an unfinished work, which the performers here respectfully leave unfinished, tailing off at the exact point that the score does. Which is all to the good, in my opinion, as somehow it seems to work better like that than if someone had come along and finished it off for him.
Originally, it was not specified for what instruments The Art of Fugue was intended, so anyone interpreting it has been given a free hand. That applies with a vengeance to the ensemble who has put this little lot together - and it's an arrangement that works very well. You've got harpsichord, organ, string quartet, chamber ensemble, the lot - and each one sounds as though it *ought* to be the way it is. Don't ask me to explain - go ahead and listen to it and appreciate it.
As for the Musical Offering, it comes from very much the same sort of direction, but seems to have been written more for the purpose of others, as opposed to being written, like The Art of Fugue, for himself. Of the two works, it's not as intellectually satisfying, but from the aesthetic standpoint it's easier to appreciate without a degree in mathematics.
The only other work of Bach's that I have experienced that remotely resembles these is the Goldberg Variations. I would be interested to hear of anything else he wrote that's so finely structured like this.
Finally, I have to mention that the price is in keeping with that of the others of this series, which has proven repeatedly that cheap does not mean nasty. Look out for these DUO editions, as they are like as not a worthwhile addition to your collection.