(such as that practiced in the modern analytical humanities) becomes
secondary. Yet this self-signification remains distinct from formalist art-
historical methods, which Riegl established with the idea that form would
express the externalWeltanschauungof a given culture. Non-semiotic
expressions of perceptual culture, such as geometry and music, do not
bring the outside world into the subject. Rather, they enable the sensory
recognition of self.
This self conceives its subjectivity not as a disembodied abstraction, but
through the soul’s mediation of sensory data. This becomes evident in ibn
al-Haytham’sOptics.His description of intromission as paradigmatic of
human psychology resonates with precepts introduced by the Brethren.
Despite the experimental orientation through which theOpticsencourages
the reader to verify the author’s observations, ibn al-Haytham presumed
that sensible entities were prone to error. He saw the sensory world as
inherently corrupt and unstable, as opposed to the imaginary world that
emerges through the certification of reason. For him, the sensible does not
exist in reality. Conversely,“the imagined form is grasped according to its
truth, and does not continuously change with the variation of whomsoever
imagines it.”^71 In contrast to our contemporary understanding, the most
true Real is not embodied in materiality, but in imaginality.
Thus objects do not exist in their external quiddity, but are understood
as coming into being in the mind. This becomes clear in the divergence of
ibn al-Haytham’s from the previous Aristotelian model. In thePhysics,
Aristotle defines space (topos) statically, as the“innermost motionless
surface of the containing body that is in contact with what it contains.”^72
In contrast, for ibn al-Haytham the perception of space required the
perpetual movement of the eye and the spectator to consolidate informa-
tion provided by“glancing”physical vision. He conceived of space as an
imagined void (al-khala al-mutakhayyal), and geometry as an immaterial
body. Space loses its concrete relationship with tangible reality and
becomes a geometrical abstraction representing the void.
This geometric conception of space makes the seeminglyfixed position
of an observer inherently deceptive both through the positioning of the eye
and through recognition of the three-dimensional body.
When sight perceives a body surrounded by intersecting surfaces of which one is
plane, then assuming the plane surface to be frontally facing the eye, and the
remaining surfaces that intersect the frontal surface to be either perpendicular or
inclined to it in such a way as to converge behind it, so that only the frontal surface(^71) El-Bizri, 2005 : 201. (^72) Quoted in El-Bizri, 2005 : 208.
292 Mimetic Geometries