Although they are often discussed, recorded, and published as a collection, the six concertos encompassing the so-called Brandenburg Concertos were not written all at once, nor for the same ensemble. Scholars suspect that Nos. 1, 3, and 6 may have been written much earlier than the others, perhaps dating from Bach's Weimar period (1708-1717), while 2, 4, and 5 most likely came from Cöthen. Bach later put the six concertos together and dedicated them to the margrave of Brandenburg, hoping to get a new job out of it. (He did not.) In fact, the only commonality among the six is the use of a three-movement, fast-slow-fast design; this indicates that the Brandenburg Concerti were based on Italian concerto format. Beyond that, they have nothing in common, and, in fact, among the six, there is as much variety as you can find in any six works by Bach.
Brandenburg Concerto No. 2 might be the most popular of the six for its brilliant scoring. This is an example of a common orchestral genre of the Baroque known as the concerto grosso. (The same is true for Brandenburg Concerto No. 5). A concerto grosso utilizes two ensembles, one large and one small. The large one is called the ripieno or tutti; this includes the orchestra. A group of soloists comprise the smaller group, entitled the concertino (meaning little concerto group). The number of soloists and instruments used was entirely up to the composer to decide. Some composers, like Archangelo Corelli (1653-1713), always used the same instruments in the concertino (for Corelli, it was always two violins and cello, plus continuo).
In the present case, Bach's ripieno includes solo flute [originally recorder], trumpet, violin, oboe, and continuo. (The continuo is never omitted, as it provides the harmonic foundation of the entire piece.) The trumpet part is very virtuosic, written to employ a style of playing known as "clarino playing," in which the trumpeter played in the highest range of the instrument, and used quickly-changing lip pressure to change the pitch of the instrument. (The trumpet of Bach's day was a long tubed instrument without valves, which were added around 1815.) Today, we normally hear a piccolo trumpet (sometimes called a "Bach trumpet"), which is pitched higher to play these passages more easily; however, the tone of the instrument is quite brilliant, and tends to dominate the texture whenever it is played.
Brandenburg Concerto No. 2 provides an excellent example of Bach's use of a ritornello. (See also the discussion of the ritornello in the Credo section of the Mass in B Minor.) Bach was an unofficial student of the composer Antonio Vivaldi (1678-1741), whose works he copied by hand (the best way to get copies of music in those days) and sometimes restored. One of the hallmarks of Vivaldi's style is his use of orchestral ritornellos, not just in his concertos (as in the concerto Spring from The Four Seasons), but sometimes in his sacred music (as in the first movement of his famous Gloria). Vivaldi typically began his concertos with a full statement of the orchestral ritornello (sometimes even two full statements), then in between solo passages, he would bring the ritornello back again, though often each subsequent appearance was a bit shorter than the previous. Bach probably got the idea of using a ritornello from studying Vivaldi, and even in this piece, you'll see that some ritornello statements are indeed shorter than the first. Here is the ritornello which opens Brandenburg Concerto No. 2:
What's interesting about this concerto is not necessarily the use of ritornello, although that certainly is the most recognizable aspect. What interests me is that Bach uses a second theme which he also treats as a ritornello, that is, a recurring theme, although this one appears exclusively in the instruments of the concertino (the soloists):
At the first entrance of each soloist (violin, oboe, flute, then trumpet), each initially plays this theme, and later variations also appear. All in all, we will hear this "solo ritornello" a total of eight times.
There are three points I'd like to make about these two themes.
Because of these three ideas, Bach creates an unusually tight, uniform movement, making it difficult for the listener sometimes to distinguish between the "solo" passages and the ripieno.
The second movement is unusual in its scoring. Whereas in the previous movement, we could sometimes not distinguish between the ripieno and the concertino, in the second movement this issue is moot. there IS NO ripieno. The second movement, an andante, is scored for three soloists plus continuo. the bright timbre of the trumpet is omitted to create a more intimate setting and to provide strong contrast with the two faster movements. Further contrast is created by Bach's choice of D minor as the key for this movement. The movement is a minuet, a medium tempo dance in triple meter. (3/4 is most common, which is what Bach uses here.) The thematic content is extremely tight here, even more than in the first movement, which only contained two basic themes. In this case, everything comes out of the first six beats of the violin line:
Hard to believe? It's true. The only part in this movement which is not derived from this is the constantly rocking bass line, which maintains the flow of the piece, clearly establishes the harmonic progression of the music, and once again creates a perpetual-motion feel.
In contrast to the first movement, there is no trouble in distinguishing between the concertino and ripieno in the finale. The soloists dominate - completely. In fact, the ripieno is barely noticeable, and is completely silent until measure 47! And leading the soloists is the trumpet, silent throughout the andante but making its presence known from the first measure of the third movement. (The trumpet also has the last say to close out Brandenburg No. 2.) There is a single primary theme here, which is introduced by the soloists like the exposition of a fugue, in the order trumpet, oboe, violin, flute:
Whatever solemnity or sombre mood may have been left at the end of the andante is surely blown away here!