THE ELECTRONIC WORKS OF GYÖRGY LIGETI AND THEIR ...

Here it becomes evident that there is an axis of symmetry around 1'40.7", and
furthermore, the material which surrounds this axis derives from that which first occurred
in Section B at 1'10". Ligeti retrogrades the material from 1'10" to approximately 1'23"
(the end of Section B), and uses this to approach the axis of symmetry, saving the original
form for the other side of this axis. Thus the retrograde statement begins at 1'27.7" and
continues to 1'40.7" while the prime form begins at 1'40.7" and continues to the end of the
section.
The intervening material between 1'23" and 1'27.7" consists of similar material, but
transposed; this is most noticeable in the Type I material, which can now be seen in the
register between 3614 Hz and 5886 Hz, significantly lower than anywhere in the B
section, where 6022 Hz was the lower boundary for this type of material. This additional
material resembles the original form of the Type I material, accelerating the pace of
glissandi; moreover, it continues, and thus appears with the retrograded form of the
original excerpt leading into the axis at 1'40". This additional material also appears in the
continuation after this axis, now in its retrograde form, but along with the prime form of
the larger excerpt.
This combination of retrograde and prime forms resembles the stated form of the
entire piece, and is one of the first connections between the mid-level and large-scale
structure of the composition. Here, however, the prime and retrograde are successive,
and will thus make an invariant shape when reversed in the second half of the piece (i.e.
the ideal shape of this passage as a whole will look and, moreover, sound the same when it
is retrograded). The uneven filtering on each side of the axis of symmetry will, however,
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