Stephen takes seriously Aristotle's theory of light/color/vision/translucence, and ignores utterly the modern scientific view of atoms and electromagnetic vibrations.
Berkeley to Patrick, 1923:
"The archdruid then explained
the illusion of the colourful world,
appearing to fallen men
under but one reflection
of the several iridal gradations of solar light,
that one which it had been unable to absorb
while for the seer beholding reality,
the thing as in itself it is,
all objects showed themselves
in their true colours,
resplendent with the sextuple glory
of the light actually contained within them."
For Joyce there must be some supreme riddle hidden here, more deeply than anyone's guessed.
"Ineluctable [impossible to struggle out of]
of the visible:
at least that
if no more,
thought through my eyes.
Signatures of all things
I am here to read...
Limits of the diaphane...
[G&S] 'Aristotle: the ear participates in (and thus can modify) the substance of what it hears, but the eye does not... sound and taste involve a "becoming" or intermixture of substance and form, in the perceptual image'
'the substance of a thing perceived by the eye is not present in the form or color of the perceptual image (in contradistinction to sound and taste)'
we now view both light and sound as vibrations with very similar properties: color/pitch/wavelength, brightness/loudness/amplitude. the two eardrums allow minimal stereo separation, compared to the eye's lens with thousands of 'eyedrums'
so how can the ear "modify the substance of what it hears"???
is he saying 'light is weightless'?
nacheinander: sequential in time (sound)
nebeneinander: side-by-side (vision)
the diaphane (the translucent medium) is 'not something peculiar to air or water, or any of the other bodies usually called translucent, but is a common 'nature' and power, capable of no separate existence of its own, but residing in them, and subsisting likewise in all other bodies to a greater or lesser degree... But it is manifest that, when the Translucent is in determinate bodies, its bounding extreme [limit] must be something real; and that colour is just this 'something' we are plainly taught by facts-- colour being actually either at the external limit, or being itself that limit, in bodies... It is therefore the Translucent, according to the degree in which it subsists in bodies (and it does so in all more or less), that causes them to partake of colour. But since the colour is at the extremity of the body it must be at the extremity of the Translucent in the body'
so all colored bodies have some degree of translucence in them, the more translucence the less color? and the color is at the real boundary-limit of the body...?
what were the translucent substances known to Aristotle? air, water, ice, oil, honey, amber, crystals, glass, jellyfish? which of these had he witnessed transforming to greater or lesser translucence, when heated or cooled or mixed or whatever?
we now explain that translucence in terms of electron orbitals that absorb, reflect, or transmit various frequencies of light. are there general principles for how to increase or decrease translucence? did Aristotle hope there were?
isn't Stephen asking very different questions than Aristotle intended, about reality and art? for Joyce, one of the most critical insights was about language... as a form of signature?