March 21st is J.S. Bach’s birthday.
Bach is one of the greatest composers of both secular and religious music in European history (not to mention being the most renowned organist of his day).
With the change in musical styles from Baroque (polyphonic) to Classical (homophonic) soon after his passing, he was largely forgotten for a time:
“After his death, Bach’s reputation as a composer at first declined; his work was regarded as old-fashioned compared to the emerging classical style. Initially he was remembered more as [an organist] and teacher.
During the late eighteenth and early nineteenth century, Bach was widely recognised for his keyboard work. Mozart, Beethoven, Chopin, Robert Schumann, and Felix Mendelssohn were among his most prominent admirers; they began writing in a more contrapuntal style after being exposed to Bach’s music. Beethoven described him as the ‘Urvater der Harmonie,’ ‘original father of harmony’.” 
His religious music is now used in churches all over the world, and in performances of religious music outside of formal services as well (not to mention his enormous body of “secular” music — so spiritual in its own way).
Today, Music students studying harmony are taught the “Bach” rules — the personal rules and choices Bach himself followed in organizing his multi-voiced (polyphonic) compositions. There are polyphonic traditions outside that of Bach’s — Early- and Colonial American writing, for example (see: Jeremiah Ingalls; William Billings, etc.) — that follow different rules, producing a distinctly different “sound.” But Bach’s own style became the standard (or its basis, at least) and still is today.
When I was a music student at City College of New York in the early ’70’s, I kept getting grades on my assigned musical harmonizations that were very frustrating, until I finally realized that I wasn’t being asked to come up with the most creative or original solutions; I was simply being asked to follow the rules! After that, my grades improved noticeably. And those rules were Bach’s rules (especially in “Theory” I and II classes).
Yet, despite being a composer of music for Christian services, Bach saw himself as continuing in the tradition of the Levites, who created and performed music for the First and Second Temples in Jerusalem:
“We…know from comments [J.S.] Bach wrote in the margins of his family Bible that he saw the musicians of the Temple in the Old Testament as archetypes and models for the kind of church musician he aspired to be…” 
It’s an interesting piece of information to consider, particularly at this time of the year in the annual cycle of Torah readings, in which one of the main current themes is the Mishkan (“Tabernacle”) that served as the model for both later Temples (and for the Temple in Ezekiel’s vision) and also served in many ways as the architectural model or basis for synagogues and for many churches.
What was it that Bach saw the Levite-musicians doing? He saw them not only performing in a holy place (i.e. the Temple), but specifically during the performance of the essential devotional acts — the sacrifices. One might note that sacrifices could be done without music, whereas music is an essential part of synagogue- and church- services. But it would also be true that historically, music came to be an integral element of the services very early; the Psalms, for example, were originally written to be performed during Temple sacrifices. Also, the primary concern of the Levites wasn’t “art for art’s sake,” but “art” for the sake of worship. This certainly included aesthetic concerns, but aural beauty wasn’t the end in itself. So, perhaps, Bach likewise felt that his “art” wasn’t, in the end, for purely aesthetic concerns, even if few composers have ever reached Bach’s aesthetic heights (and variety). Rather, he seems to have felt that his “art” was an act of personal devotion in itself; an embellishment to the prayers meant to lift his congregation (and us) to higher levels of worship.
Yet, Bach doesn’t say that he saw himself as a “Kohen” — i.e. as the one performing the actual sacrifice. Rather, he saw himself as a “Levite,” bringing additional spirituality to the worship through his music, as the Levites had done.
Rabbi Jonathan Sacks, chief Rabbi of Great Britain, concurs:
“Goethe said, ‘Religious worship cannot do without music. It is one of the foremost means to work upon man with an effect of marvel.’ Words are the language of the mind. Music is the language of the soul.” 
The Zohar expresses the same thought:
“Rabbi Yehudah said, ‘Why are the Temple-singers called Levites? Because [when they sing] they’re joined [lava/nilvim] with G-d as one. The soul of him [or her] who hears their singing is joined [nilvah] with G-d as well’.” 
It certainly seems to parallel Bach’s own musical intentions.
We might infer much from this about how Levite-musicians saw themselves and their work.
Most of all, we should consider what we ourselves bring to worship to lift ourselves, and those around us, to higher levels — to join ourselves to G-d.
 Zohar 2:19a (on parshah Sh’mot; the Zohar is traditionally published in 3 volumes).
[*] The Soncino (5-volume) translation (from vol. 3, p. 60) is as follows:
“Why were the singers here below called ‘Levites?’ Because they are joined closely (‘lava’ — ‘to be joined to’ ; see also Ber./Gen. 29:34) and united with (the singers) above in absolute [unity]. He who hears their singing, his soul is [also] joined to the upper world.”
[**] Zohar.com (online edition of the Zohar in Hebrew or Aramaic and English) has another translation, which I’ve revised slightly:
“Rabbi Yehuda said, ‘Why are the singers below called Levites? Because they are attached (Heb. nilvim) and joined above as one. One who hears [their singing], his soul [too] becomes attached and joined above’.”
See: Zohar.com, Shemot, perek (chapter) 46, par. 333
For more about the Levites, music in the Temple and music in Judaism, see also:
On the Temple itself, see: