DICTIONARY OF MUSIC - El Atril

496 INVERTIBLE COUXTEEPOINT INVERTIBLE COUNTEEPOINT
be inverted without disturbance of its expressive
qualities. It is not an example of regular in-
version, but one in which Bach has taken the
two limbs of a fugue subject (that of Ko. 16
from the ' Forty-eiglit ') and used them, rather
freely inverted, as the counter-subject :
Subject.
^^^^m^^m^ ^sflktf
Instances need not be further multiplied to
prove the striking and consequently dangerous
nature of melodic inversion, or to show its best
use. Neither need further quotations he made
to prove that its dangers are not shared by
ordinary harmonic inversion. The contrast of
the two, however, would not be just, or at all
complete, if we omitted to point out, that, although
the prevtiiling characteristic of ordinary
inversion is its extreme usefulness, there arc rare
instances in which it also achieves a certain
delicate expressive significance of its own. One
such is to be found in a movement in Part I. of
Bach's Cliristuias Oratorio, where two oboe parts
which stand thus in the introduction :
acquire a new thoughtfulness in their inverted
form ^ at the close of the movement :
Some account of the earlier stages of the art
of inversion, as expounded b}' two notable 16th
century theorists, and exemplified in the works
of the greatest composer of the golden age, may
be appropriately attempted here.
Early use of Tnvertihle Counterpoint.—The
custom, in the early days of Organum and
Dlaphonia, of freely doubling the vox organahs
an octave above or the vox2rnncipal}s an octave
below (see Diaphonia), forms virtually the
prototype of ordinary inversion. It seems
pjrobable that its practical origin lies in the
natural conditions of vocal compass. When
the words of a motet or mass were passed from
part to part, their musical couuter^iart would
1 This aaeful and easy inversioo of two upper parts, while the
lia-w reinaiiifl tmclin-nged, was constautly used by Bach. It often
eeiufl aa if the pxicencies of compasa iL](*ne dictated it. but iu such
an instance a.-) that quoted above, it ia a tfratuitoua inveraiou,
juatifled only aud entirely by ita eiquiaite beauty of effect.
go with them ; the accompanying parts would
then fall into other relative positions, and inversion
of some sort would soon be discovered
and prove useful. The other (melodic) manner
of inversion doubtless first arose with the mere
exercise of contrapuntal ingenuity ; it ia safe
to assume that it was greatly fostered by the
canonic devices so dearly loved and diligently
cultivated in the 14th century, if, indeed, it
did not originate then. It might peidiaps have
been expected that the usefulness and fascination
of inversion would have claimed for it
gi-eater attention in the earlier days than it
actually received. Its use in the 16th century,
as will be seen presently in the extracts from
Palestrina, was quite masterly but never very
systematic. As to the theorists, Ornithoparcus
(in 1516) has apparently no mention of the
subject of inveision at all in his delightful Micrologus
; but a limited number of artificial manners
were sufficiently common to be minutely dealt
with by Zarlino in 155S. Of these some details
may be liere given, especially as our own iloi'ley
explained the subject a few years later to English
students in his Plaine and Easie Introduction
as ' a manner of composition used among the
Italians, which they call contrapunto dopjtio, or
double descant, which being sung after divers
sortes, by changing the partes, maketh diverse
manners of harmony : and is found to be of two
sortes.' Both Zarlino's and ilorley's two sorts
prove to be really three, as their first sort is
divided into two manners, one of which (as the
former author says in his Istitutioni annonichc),
' when the parts are inverted continues with the
same intervals,' the other 'with variations.' Both
theorists proceed to suggest that, in the first
manner, the inversion is to be efiected by transposing
the higlier part a fifth lower aud the
lower an octave higher, while in the second
manner the higher part should be taken a tenth
lower and the lower an octave higher. These
two kinds are virtually double counterpoint in
the twelfth and tenth respectively, indeed,
Morley gives them these names ; and the description
of the latter as being 'with variations'
simply refers to the modifications of intervals
necessary to preserve tonality when transposing
any part a tenth. The other sort of 'double
descant,' described by both theorists, is practic-
ally inversion by contrary movement, already
referred to at length in this article ; but some
of the examples are planned, by an accumulation
of device, not only to invert in a variety of
ways, but also to make strict canon, sometimes
direct and sometimes by contrary movement.
A clear idea of the evolution of this art is only
to be given by rather extensive quotation.
Morley's examples of the first two sorts are too
long to quote in full, but a few bars will give
an idea of their vigorous character as well as
show their exact method of inversion as laid
down by both Zarlino and Morley himself: