Godasalwayselsewherefromtheperceiving subject, inward mimesis enables
geometry to make God present in the perceiving soul.
The replacement of visual theories of extramission with those of
intromission developed by ibn al-Haytham increased the scientific
basis for understanding perception as apprehending and processing
the world from the glancing toward the contemplative gaze. As with
the Brethren, the sectarian implications of ibn al-Haytham’sthought
are unclear. Like al-Kindi, ibn al-Haytham grew up in Basra, indicat-
ing Sunni roots with strong ties to Mu’tazilite experimentalism
absorbed by Ash’ari thought. But he worked in Fatimid Cairo at a
time when the Abbasid ruler al-Qadir in Baghdad had recently under-
scored the Sunni rejection of the Isma’ili esotericism of the Fatimids.
Theologically, ibn al-Haytham’semphasisonimaginationasthelocus
of form could correspond to multiple positions. His deep interest in
experimentalism, particularly his concern with using evidence to
explain the errors in vision, reflects a Mu’tazilite perspective. Yet the
distinction he subsequently makes between the apparent form of
things and their formulation as real entities through the imagination
suggests Platonic ideas deeply integrated in Isma’ili thought.^53 His
emphasis on the temporal nature of sight also corresponds with the
occasionalism of Ash’ari theology, asserting that no accidental state of
matter persists more than one instant and that any continual state is
perpetually renewed through the will of God. While the diverse geo-
graphy of early uses of muqarnas attests to an association with
Ash’arism, Tabbaa suggests that this association quickly dissipated.^54
Yet meaning may persist.
Many literary texts using transmedial metaphors based on visual and musi-
cal pattern reflect the perpetual fungibility ofmedia. Al-Farabi describes the
development of music from its basic harmony to its full embellishment through
transmedial comparisons with the work of an artist who sketches, organizes,
and then completes it by adding its colors; the warp and weft of fabric; and the
bricks of buildings.^55 An eleventh-century writer, al-Hasan al-Katib, elaborates
on the idea, comparing the process of detailing the basic order of a musical
piece with the dyeing and further embellishment of a textile. He then inverts the
analogy to describe connoisseurial apprehension:
An old song is like an ancient fabric, the merits of which are familiar and the beauty
of which becomes more apparent as one continues to gaze upon it and consider it:
(^53) El-Bizri, 2012 :46–47 n. 109. (^54) Sabra, 2009 ; Tabbaa, 1985. (^55) Wright, 2004 : 363–367.
Isometric Geometry in Islamic Perceptual Culture 287