DICTIONARY OF MUSIC - El Atril

INVERTIBLE COUNTEEPOINT INVERTIBLE COUNTERPOINT 503
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The great usefulness of this kind of counterpoint
is also well illustrated in such learned
fugues as the A minor from Bach's Forty-eight
quoted at p. 495. The following fragment of
double counterpoint, which appears at the second
.and third entries of tlie subject,
and an analysis of the whole fugue reveals its
almost inexhaustible possibilities,^ in such de-
"vices as these :—
ft^
DouUcCoiinta-jwifit at the Tirrlfth.—The chief
practical jioints to note in this in"\'ersion are :
(1) that, in it, thirds become tenths and vice
versa, so that consecntive thirds and tenths
may be freely used ; (2) octaves and fifths are
also interchan£;eable, each inverting into the
-other ; (3) sixths are to he used with peculiar
caution as they invert into sevenths. Its chief
characteristic, and probably its chief usefulness,
are both to be found in its power to ett'ect or
' It is the coTi/rari/ conjunct movement which chiefly accounts
for the great reaonrces of this particular counterpoint. It will
be seen that it is iuvertible in a variety of ways other than the
tenth, and that when the subject ia taken in contrary movement
and in close atretto, the use of the first counter-subject never fails.
suggest a subtle modulation to a nearly related
key (the dominant or subdoniinant, as the ease
may be), since while one of the parts remains
stationary, the other is transjiosed a twelfth up
or down. Special allowance for this effect should
be made in the model, especially at the cadence,
The device of a falling fifth adopted by Jlorley
ill the Iburth bar of tlie passage already quoted
(at p. 497), is excellent and should be noted,
as when the lower part is transposed a twelfth
higher a perfect cadence in D minor is efiectively
secured. The following fragment is so planned
as to infer three ditterent cadences (in A minor,
F major, and C major respectively) in its model
and two inversions. It is not always necessary,
^J^
however, to suggest modulation. It may be
avoided either Viy careful omission of the note
that would etfect the modulation in inversion
(subdoniinant or leading note), or else by deli-
berate alteration of that one note in the inverted
form. Tliis hach has done in the following
beautiful tri}ile counterpoint, an instance of
particular gi'ace and significance :
m
5fe=3t?-^
sSTsss SIS' ^ "Kis ^^^i
m
Mi
^^^^^4m^w^4-
..^^
Jt.— \
• etc.
Inirrsio'/i hy Contrai-ij Movement.—So much
has already been said in the first part of this
article on this important variety that it only
remains to name the chief points to be observed
in construction, and the ways in wliich inversion
may best be eifected.
(1) Concords must prevail at the accented
points, and only passing discords may be introduced.
^STaturally no suspended discords are
possible, for the simple reason that in the inversion
the suspension wordd fall upwards, and
" It ia the cadence in all double coiinterpoSnts that naturiiDv
need.9 closest atteution, for it is there that flciriicsa is iimst
desirable.