In White Mythologies, in part a disquisition on poetics, Derrida quotes Du Marsais on metaphor:
When we speak of the light of the mind, the word light is to be taken metaphorically; for just as light in the proper sense enables us to see corporeal bodies, so does the faculty of knowledge and perception enlighten the mind, and put it in a position to make sound judgements. Metaphor is then a species of trope, the word used metaphorically is used in some sense other than its proper sense: it dwells 'in a borrowed home', so to say; something which is essential and common to all tropes.
But say we reverse this; that is take light not to be metaphorical but literally; then is it not, in rough terms, with Kant that it is the light of the mind thrown on the object that makes the the object visible to the subject and not the light thrown on it from some other - say the sun, or candle or a smoky oil-lamp?
And one might note here, that Empedocles in early antiquity makes a claim that one instantly discounts: that the eye perceives an object because of the light sent out from the eye:
A single sight comes from both eyes
As when someone preparing for a journey prepares a lamp
A flame of blazing light in the wintry night
...And shines across the threshold with unvarying beams
Since, one thinks, in the day I see because the sun is there up in the sky and casting its light on all, and at night when it sets and sinks we do not see at all; and so we light an oil-lamp and by its steady flame we see again; and when we cover it we do not; thus it is seems a perfectly sensible judgement (and hardly counting as one), and a judgement that Du Marsais made in the quote above, that it is light from some other source that allows for sight.
But the crux of the problem for me, is that Empedocles being an inventor of the hypothesis of the four elements, is hardly going to make such a childish slip; it's very absurdity should give us pause that there is something behind his theory of perception that isn't being brought out by a simple-minded literal reading; and a more sophisticated reading appears to be called for.
I've suggested a reading via Kant (juxtaposing or yoking (as in the sense of metaphor) two unlike philosophies to throw some light on the first); but another possibility might be Suhrawardis School of illumination which being an emanationist theory of light might be another point of departure (or entry).
What readings have been given for this puzzling fragment of Empedocles, that allows harmonising a light from the eyes, and the light from the sun; or the light from within and the light from without?
If any at all?