I suppose one would have to ask if he ever recovered and was able to say whether or not these were the things he actually saw. this all occurs to me because the act of representation itself requires visual feedback, and if the artist is hallucinating while he paints, what is painted will not be the hallucination but a kind of redoubled representation of the disorder of hallucination. you know? like a hallucinated hallucination: a feedback loop of obsessive obsession. how do you paint what you see when you cannot even see the paint?
I don't know if this has anything to say about "mental illness" and honestly I don't care so much but it might add a layer of subtlety to, say, Deleuze's "schizoanalysis" which occurs at the level of representation and calls into question any representability whatsoever, and makes of schizophrenia a kind of representational/associational analogy rather than a constellation of symptoms.
in any case, clearly I drank too much coffee this afternoon and I hope I can go to sleep by 8 because I have to get up early and grade papers.