It is practically certain, however, that the Brandenburg Concertos were performed by the princely Kapelle at Cöthen in Bach’s presence, for the composer had been wise enough to make copies of his scores. They are not concertos in the modern sense of the term, but continuations and developments of those “concerti grossi” of masters like Torelli, Vivaldi, and Corelli. In various permutations and combinations they contrast groups of solo instruments (the “concertino”) with the background of the “tutti.” The “concerti grossi” of Handel furnish examples of the same principle of balance and diversity. The fact that none of the Brandenburg Concertos is in a minor key and that somber moods are rare, points to the probability that they were written for entertainment purposes.
Their variety is astonishing, with no two quite alike. The first, in F major, is the only one which calls for horns; and for the performance of this concerto two horn players were specially engaged at Cöthen. The second, likewise in F, requires a trumpet—the solitary appearance in the entire set of this instrument. To choose between the Brandenburg Concertos, to determine their relative musical worth is impossible. Yet in some respects the sixth, in B flat, if perhaps the least frequently played, is the most unusual. No violins are used in its scoring. The employment of two violas, two viole da gamba, and cello gives the work a peculiar dark string color wholly its own.
Let us mention here the wondrous concerto for two violins, another sublime inspiration of Bach’s Cöthen days. It is probable that it was played by the concertmaster, Josephus Spiess, and the excellent violinist, Johann Rose (who also played the oboe and taught fencing to the court pages!), with the composer conducting the orchestral accompaniment.
And Prince Leopold, himself, who not only enjoyed music but played it well, doubtless took part in the sonatas for clavier and viola da gamba. He could not do without his musicians apparently and, when, in 1718, he went to take the “cure” at Carlsbad, he had a sextet from his Kapelle accompany him. Bach was one of the retinue. The following year the Kapellmeister made a pilgrimage to nearby Halle in an effort to meet Handel, who had come to the Continent to engage singers for his operatic ventures in London. But neither at this time nor on a subsequent occasion when he tried to make the acquaintance of his great contemporary was he successful. Handel had already returned to England, seemingly far less eager to meet Bach than Bach was to meet him.