e first chorus of a university festival cantata, _Vereinigte
Zwietracht der wechselnden Saiten_, the very title of which ("united
contest of turn-about strings") is a perfect definition of the earlier
form of _concerto grosso_, in which the chief mass of the orchestra was
opposed, not to a mere solo instrument, but to a small group called the
_concertino_, or else the whole work was for a large orchestral mass in
which tutti passages alternate with passages in which the whole
orchestra is dispersed in every possible kind of grouping. But the
special significance of this particular chorus is that it is arranged
from the second movement of the first Brandenburg concerto; and that
while the orchestral material is unaltered except for transposition of
key, enlargement of force and substitution of trumpets and drums for the
original horns, the whole chorus part has been evolved from the solo
part for a kit violin (_violino piccolo_). This admirably illustrates
Bach's grasp of the true idea of a concerto, namely, that whatever the
relations may be between the forces in respect of volume or sound, the
whole treatment of the form must depend upon the healthy relation of
function between that force which commands more and that which commands
less attention. _Ceteris paribus_ the individual, suitably placed, will
command more attention than the crowd, whether in real life, drama or
instrumental music. And in music the human voice, with human words, will
thrust any orchestral force into the background, the moment it can make
itself heard at all. Hence it is not surprising that the earlier
concerto forms should show the closest affinity (not only in general
aesthetic principle, but in many technical details) with the form of the
vocal aria, as matured by Alessandro Scarlatti. And the treatment of the
orchestra is, _mutatis mutandis_, exactly the same in both. The
orchestra is entrusted with a highly pregnant and short summary of the
main contents of the movement, and the solo, or the groups corresponding
thereto, will either take up this material or first introduce new themes
to be combined with it, and, in short, enter into relations with the
orchestra very like those between the actors and the chorus in Greek
drama. If the aria before Mozart may be regarded as a single large
melody expanded by the device of the ritornello so as to give full
expression to the power of a singer against an instrumental
accompaniment, so the polyphonic