[beyonddream]

I think parent comment meant that one can’t use the eye to see itself directly without using any intermediaries like mirror or photograph.

[IIAOPSW]

Obviously, but why isn't the use of an intermediary allowed in this metaphor?

[hgsgm]

It's allowed, but once you've used a mirror to understand your eye, you don't need the mirror anymore.

[PartiallyTyped]

Technically it’s entirely possible given sufficient gravitational bending.