Hats off to Elvis and all that, but Mr. Bach really IS the king! In my opinion (never wrong yet) and that of lots of folks, past and present, JSB sits at the head of the table for European art-music. Historical stuff aside, the real reason is that his music is, for many, far and away the greatest achievement of anyone working in the Euro tradition. Next to JSB, all of the other supposed big names -- Handel, Mozart, Beethoven, etc., are, at best, mere "also wrotes". You agree?
And within the huge repertory JSB left us, the very centre has to be the two hundred or so surviving cantatas. Most professional Euro-art musicians, not to speak of the students, are pretty much clued out on this music since, in general, instrumentalists are familiar with music written for whatever it is that they play. Since the JSB stuff we're dealing with here is primarily vocal, with instrumental accompaniment, it is normally overlooked by "players". In the music world, this results in some very strange life forms indeed. Perhaps the most frequently encountered: the keyboardist who knows only a couple of preludes and fugues from the Well Tempered Clavier whatever. To you, sir or madam, our profound condolences.
And why vocal music? For one thing, singing is more integral to the development of musicianship than playing an instrument is. And the particular music at issue here was all intended to be sung, although the writing sometimes makes you wonder what manner of human Bach had in mind.
And a second reason for working on the cantatas. Because Bach was setting words, his dramatic sense often led him to harmonic extremes that could never have come up in a piece of abstract, textless instrumental music. This mostly has to do with his use of modulation. When Bach is describing death or what it's like to be destroyed by guilt, say, he doesn't write party music, let's say. If you are interested in modulation pushed to its outer limits, and dragging your aural perception kicking and screaming along with it, then JSB's cantatas are just the thing for you.
I have been studying the cantatas for several years now, mainly the arias. Most of them are beautiful (some in a masterfully ugly way), and many are very challenging from the point of view of musicianship, which is just a fancy way of saying that they are hard to learn. Beauty and brains, with low levels of redundancy and fluff. That combination puts Bach's arias at the top of my list.
To keep things in perspective though, I do realize that Bach was up to more than writing the world’s greatest vocal music. Because my interest is mainly on the analytical and theoretical side of things, I’ve edited a bunch of his most famous keyboard works in open score. And on and on. Take a look around, there are many treasures here, either for free or for cheap.