If the greatest epistemological barrier of psychology is reconciling the fact that we are dealing with the almost self-referential idea of brains analysing brains, then the same element of surprise and mischief is at play with eyes.
When I look in the mirror, the seeing eye observes itself looking, a seeming paradox which is nevertheless resolved perfectly every time.
We assume that the brain analysing other brains is a sound one: not swimming in alcohol, not impacted by disease, not in such a state of depression that its judgement is impaired. For, of course, faulty judgement calls lead inevitably to faulty conclusions - and the whole discipline of psychology is laughed out of the room.
Similarly, a damaged eye stares at itself, and its findings are necessarily erroneous. This leads to infinite regress, until I can envisage a broken eye which collects no light, and therefore cannot start the loop of the observed observing.
Why not laugh the findings of the damaged eye out of the room? It is so bad that its pupil scurries into the corner like a terrified mouse back into its hole. It is so bad that on its own it can't differentiate one huge capital letter from another at a distance of a few feet - it needs the ballast of its partner, and both require the false perspective of glasses.
Others squint to resolve the regular flcker of distant stars - for me the optician's whiteboard is a periodic cepheid variable.
I hate the broken, toiling eye - it has sucked my blood for decades with its vortex. I can't dismiss it, nor its blurred findings, because we are yoked together until the end.
How many times have I wanted you to be extinguished; the Greek riposte to a crime? When I was four, the doctors tried to fix you by disabling my other eye with a patch, and they succeeded in terrorising the rest of me.
Stagnant, morbid eye, you discolour everything, deriving your useless conclusions from nonsensical hypotheses. You distort images and I, the living four-year-old trapped in a man's body, continue to despair at the world we create between your twisted light and my compromised critical faculties.
