The so-called Christmas Oratorio is unusual for this genre. It is not a single large work, like Bach's other oratorios, but instead is really six cantatas which were performed at six different times between Christmas Day and the feast of Epiphany (traditionally, January 6). Each separate cantata uses different performing groups, emphasizing the idea that this is not one large work.
Although parts of the libretto are poetic, much of it is taken from the German translation of the Bible. Bach used portions of the Nativity story from the Gospels of Luke and Matthew in retelling the story.
The work divides as follows:
The Christmas Oratorio was written in 1723 and 1724 and first performed in its entirety in the Christmas season of 1734-1735. At this time, Bach was in Leipzig.
The Christmas Oratorio makes great and frequent use of chorales. In fact, of the 64 movements across the six cantatas, 14 are chorales.
The chorale was an invention of Martin Luther, who wanted to create a type of church music in which the congregation could participate. The members of the congregation in the Roman Catholic Church at that time (c. 1500) did not sing, but instead listened to soloists and/or a choir. A chorale is a hymn-like melody sung in German, the language Luther spoke. In its traditional usage, a chorale would have a simple, obvious melodic line (sung by the sopranos in a choir or by the congregation in church) with a basic chordal accompaniment sung by the altos, tenors, and basses in a choir, or played on the organ.
Bach didn't write any original chorale melodies, but many of his harmonizations are used in churches throughout the world, including Lutheran, Moravian, U.C.C., and Roman Catholic congregations. Bach uses chorales in all six cantatas of the Christmas Oratorio. Bach's use of chorales in the Christmas Oratorio show a great deal of variety and invention. We will look at the chorales in groups, based on similarities in the way Bach composed or harmonized them.
The first group (which is also the largest) are the traditional, four-part settings. In these settings, the sopranos in the choir (and the soprano instruments of the orchestra: flutes, oboes, first violins) have the chorale melody. Bach rarely wrote the melodies to these chorales; most were written by earlier composers, including Martin Luther himself. The altos, tenors, basses of the choir (and instruments playing in those registers in the orchestra) would play the harmonization. Many times, they would perform the same or virtually the same rhythm as the sopranos. These traditional settings sound very much like the hymns we use today in Christian churches.
The first chorale in the Christmas Oratorio, "Wie soll ich dich empfangen" or "How shall I fitly meet Thee" in English, is one you might even recognize from church. This appears in the first cantata in the Christmas Oratorio, and in the fifth movement overall. (Bach also uses this chorale in the St. Matthew Passion.) Although the words are different, the tune is known as "O Sacred Head, Surrounded" (Or, "O Sacred Head, Now Wounded"). See what this traditional type of setting looks like:
The end of each phrase is marked by the use of a fermata. Although a fermata is often interpreted as a "hold", meaning to hold that note or chord longer than indicated by the rhythm, in Bach's time this indicates the end of a phrase and a place to take a breath.
This chorale is mostly in the minor mode, meaning that it uses pitches from a scale in which the third note is lowered. Sometimes the sixth and seventh notes are lowered as well, though they are often not. Pieces written in minor are often more somber or sad in mood. This chorale is not so much sad as it is penitent, hopeful, and longing. Part of the longing comes from Bach's use of chromatic pitches, which can easily be seen in the music. This makes the setting a little more colorful and unexpected in a surprising twist, and reinforcing a feeling of hope, this chorale ends on a major triad.
The same chorale melody is used in a different way in another piece in the sixth cantata.
Another chorale which might sound familiar and which uses this same traditional, four-part setting is "Brich an, o schönes Morgenlicht" or "Break forth, O beauteous, heavenly light". This appears in the second cantata of the Christmas Oratorio. This one is different form "how shall I fitly meet Thee" in that it is mostly major, rather than minor, although the third and fourth phrases do sound more minor. In addition, the first two phrases repeat, though using different words. Like the previous chorale, this one, too, uses fermatas to mark the ends of phrases and places to breathe. You might notice that "Break forth, O beauteous, heavenly light" has very active alto, tenor, and bass parts, as did "How shall I fitly meet Thee". Although Bach makes the lower parts more interesting by giving them a lot of extra notes to sing, there is never a doubt that the sopranos have the melody.
One other chorale using a traditional, four-part setting needs to be discussed here. This one is "Dies hat er alles uns getan", or "The Lord hath all these wonders wrought". This one is not all that different from the previous two we discussed. However, it uses a melody actually written by Martin Luther, and it is one that Bach's Lutheran congregation certainly would have known by heart.
In all, including the three we've discussed, Bach writes nine chorales in a traditional, four-part manner. Every cantata in the Christmas Oratorio contains at least one of these type. These all use famous chorale melodies that Bach's congregation would have known, and they could sing along on these pieces. This is why these are usually sung at a slow tempo to make it easier for the congregation to join in the singing.
There are four chorales in this group, which includes all the chorale settings in the Christmas Oratorio in which the choir sings a traditional, four-part harmonization, with the melody in the soprano, just like in the Group A settings. However, rather than the orchestra doubling the choral parts, the orchestra plays a more active, independent accompaniment.
To compare chorales from Group B with Group A, we can look at the last movement of the Christmas Oratorio. Here, Bach again uses his famous "Passion Chorale", as it was sometimes called, the same tune he used as the first chorale in the Christmas Oratorio.
Compare this, now, to the latter version. Here, the choir sings a traditional, four-part setting (called "homophonic" in texture). As they sing, the orchestra, which includes trumpets, timpani, oboes, strings, and continuo, plays very active, busy, and independent material. You might notice that when the choir sings, the louder instruments (trumpets and timpani) generally don't play; otherwise, they might cover up the sound of the choir. Whereas in the earlier version the choir sang continuously, taking only a breath between phrases, here the orchestra plays in between chorale phrases. The texture is continuous because the orchestra (especially the violins) never stops, even though the choir is silent for a period. The combination of the choral parts and independent orchestral music creates a polyphonic texture, where multiple, independent parts are heard simultaneously. The liveliness of the orchestra and the quicker tempo overall make this version much brighter, hopeful, and joyful than the first time we heard the chorale (in Group A).
Bach uses this same technique (a traditional, four-part harmonization in the choir against an active, independent orchestra) in movements #9 and #23. In both cases, he uses the same chorale melody, known as "Vom Himmel hoch". Although these two movements use the same melody and texture, and similar harmonies, they still sound very different. in the first of these two (#9), Bach doubles the choral parts with the "softer" instruments (strings and woodwinds), but then in between choral phrases, the brass and timpani make rather bold statements. In addition, the continuo part becomes much more active. The meter here is a standard 4/4, meaning that beats or pulses are grouped in fours, and each pulse is normally subdivided in twos (if it is subdivided).
The latter version (#23) is very different. Bach uses a different key, which allows the melody (and all the other parts as well) to be set a fourth higher. The orchestra here does not contain any brass or percussion, but instead uses an overall gentler sound, created by the flutes, oboes d'amore, and oboes da caccia. The meter in this version is 12/8, meaning that the beats are grouped in fours, but that each beat is divided into three. This gives the piece more of a lilting feeling. The use of a triple subdivision of the beat, softer woodwind instruments, and G major (the key of this piece) all combine to create what is called a "pastoral" sound. You might notice that this word is similar to "pastor", which means "shepherd", or to "pasture", which also reminds us of sheep. Bach very likely did this intentionally, since this chorale is the last in the two cantatas which focus on the shepherds in the Christmas story.
Can one chorale constitute a group? In this case, yes. Group C in Bach's chorale settings in the Christmas Oratorio includes only one member, but this is still significant and worth discussing for two reasons: 1) Bach uses this treatment of chorales in many other pieces, so if you listen to more Bach, you're likely to come across it somewhere; 2) as this is the only example of this type of chorale setting in the Christmas Oratorio, it is easy to spot and to remember.
In the broadest sense, a chorale fantasia is a piece which uses a chorale melody somewhere. Usually the chorale melody is presented in long notes, so that it is recognizable. Around the melody, the orchestra, choral voices, and/or organ perform more involved parts, sometimes playing fragments of the melody, sometimes echoing, sometimes adding very ornate and complicated accompaniments. Basically, the parts not containing the chorale melody were very free - the composer could do whatever her or she wished.
Bach wrote many chorale fantasias for organ, where the chorale melody is stated clearly in a high register. But he also wrote in this style for voices, where the sopranos state the melody. This type of chorale setting is used once in the Christmas Oratorio in the seventh movement of the first cantata.
This chorale-fantasia uses the same melody as in "The Lord hath all these wonders wrought". The melody, as you recall, was written by Martin Luther, and would have been easily recognized by Bach's Lutheran congregation. This fantasia uses a texture called "arioso", a texture which is partly lyrical and expressive and partly recitative or speech-like. In this case, it is obvious which sections are lyrical and which are speech-like, because Bach only uses the chorale melody in the lyrical sections. A solo soprano sings this melody, which a solo bass takes the recitatives, or speech-like sections. The lyrical sections also employ an oboe, oboe d'amore,and continuo in imitation, but use very sparse, bare accompaniment for the recitatives.