The so-called “hidden” chorales that appear mainly in Bach’s sacred music in the instrumental parts where they are untexted (Bach, in his scores, does not supply even a hint as to their derivation) are slowly being ‘discovered’ and add yet another level for understanding and enjoying Bach’s compositional expertise and appreciating the unfathomable density of Bach’s musical thoughts. There are various categories for these ‘hidden’ chorales, some of which are more easily recognizable and others which have almost defied discovery until recently.
The most obvious untexted chorale quotations involve the playing of the entire chorale melody from beginning to end as in BWV 19/5 where the tenor sings an aria accompaniment to the trumpet’s playing of “Herzlich lieb hab ich dich, o Herr,” the 3rd verse of which is referred to here and also sung at the very end of the SJP (BWV 245). This is not the chorale featured in this cantata and it (the trumpet part) is not marked with even the smallest hint as to which chorale is being alluded to here. Bach must have assumed that all of the performers and the members of the congregation would make the appropriate connection in their minds and hearts.
Such complete textless citations of famous chorale melodies are not very common, but another striking example of this could be the introductory mvt. to BWV 244b [Frühfassung – Johann Christoph Farlau’s copy from 1756] which has only an organo part (no ‘soprano in ripieno’ part) containing the chorale melody for “O Lamm Gottes, unschuldig” with most of the text omitted (for all the other choral parts the text is always present.) There is a good possibility that Bach tried to perform an untexted, instrumental version of this chorale melody, only later to reconsider and use sopranos to sing the words clearly (perhaps too many people in the congregation in the earliest performance missed this chorale citation because it did not stand out sufficiently without the words and the additional support that voices in the highest range could bring to bear on emphasizing this chorale.
Much more common are the instrumental citations or allusions to a chorale when they are used as imitative, motivic material derived from the main chorale melody as in the introductory mvts. of many chorale cantatas. These quotations usually appear ‘per diminutionis’ (in ‘diminution’ or shortened time values – with more quickly moving notes: eighth notes instead of quarter notes, for instance.) These serve a structural purpose to help unify the various lines of the chorale, and/or to prepare for the entrance of the main chorale melody in augmented form (longer note values: quarter or half notes, for instance.) Most often these snippets consist only of a direct quotation of the opening line of the chorale melody: the incipit of the chorale melody. These can occur in the inner mvts. of a cantata as well, where they help to unify the disparate musical elements of the recitatives and arias. Such quick citations of the chorale’s melody can either be sung or played (the bc might quote such a phrase while the recitative is being sung to other notes that are unrelated.
By far the most difficult ‘hidden’ references to chorale melodies are those involving “Umspielung” which is a technical term used by Bach scholars to designate a special kind of elaboration or embellishment of a chorale melody. In essence, this is a type of variation where the variation of the melody still contains the melody in the same sequence of notes according to which it is recognized; and yet, because of Bach’s elaborate technique of ornamentation, it is not quickly perceived as a direct modification of the original.
These “Umspielungen” [the verb, ‘umspielen’ can mean in soccer (and possibly also basketball) ‘to dribble around’ or literally ‘to keep on playing as one moves/goes around’ ‘without separating oneself from the main object/idea/(melody), to play around --around the outside of—an already moving object/idea’] may represent one of the highest achievements in Bach’s variation technique.
A list of examples of mainly (but not only) this type of “Umspielung” follows directly below. The answers or solutions will be presented on a separate page, which will indicate the specific source of these examples: BWV #, name of Bach scholar who first identified, the chorale melody with its notes clearly marked.
In the German sources, these ‘hidden’ chorales are described in a rather matter-of-fact manner (‘selbstverständlich’) as if this is just another, understandable aspect of Bach’s genius. The English-speaking commentators are frequently amazed at the ‘instrumental quotations of chorale melodies’ referring to some of them as ‘thinly disguised references,’ ‘fleeting and subtle references to an associated melody,’ ‘veiled allusions to phrases from the chorale melody,’ and the one I particularly like: ‘like comets’ tails.’