The "Little Organ Book"--unpretentious title for one monumental collection--was conceived early in Bach's career as a series of preludes appropriate for each season of the liturgical calendar. Bach's grand conception for the cycle is revealed in the titles of 164 planned chorales with space for each one eventually to be added. Although never completed, Bach's "little" book does contain forty-six chorale preludes representing some of the most beautiful in that genre. They include four chorales for Advent, thirteen for Christmas and New Year, thirteen for Holy Week and Easter, and fifteen for other events.
Whereas the Orgelbüchlein was dedicated to "the Prince of Anhalt-Cöthen," most of it was composed during Bach's prior appointment in Weimar. His official duty in that city was as organist, and Bach's greatest compositions for that instrument date from this period.
On the title page of Orgelbüchlein Bach writes, "so that the organ student might learn how to develop a chorale, in various ways, and at the same time gain experience in the technique of playing the pedals, which in each of these preludes is treated as entirely obbligato." By supplying his students with an independent pedal the composer indeed promotes technique. But the Orgelbüchlein transcends fancy footwork to include every type of cantus firmus combination imaginable. Bach's "little" book has become the composer's model for cantus firmus texture, not to mention the bread and butter of functional music within the Protestant tradition for the last two hundred and fifty years.
Expressing the Affekt
But we know that Bach's purpose for the Orgelbüchlein was more than player's technique and counterpoint; he was interested in the "affect" suggested by the text of each melody. We know this because one of his organ students from Weimar, Johann Gotthilf Ziegler (1686-1747), recalls that Sebastian instructed his students to play the organ in such a manner as to express the essential mood, or Affekt, of the text.
Figural Function of Canon
Bach's use of canon in eight of these chorale preludes assumes, in view of Ziegler's recollection, a fundamental role for canon as figural device contributing to the emotional state envisioned by the composer. We consider, therefore, the poetry of these chorales as essential to our understanding of not only Bach's music, but also his choice to set them in canon.
The canonic prelude In dulci jubilo, for example, is an amplification of the refrain trahe me post te, "draw me after thee," while the running triplets rejoice at Christ's birth. In Gott durch deine Güte canon represents the Wort recht bekannt, "Word growing in us." In an exegetical gesture worthy of Luther himself, Bach uses canon in O Lamm Gottes unschuldig and Christe du Lamm Gottes to recall the prophecy of Isaiah: "He was led like a lamb to the slaughter" (Isaiah 53:7).