That's not a proof by any definition of the word I understand. Imagining something does not prove the existence (or otherwise) of that thing. [edit] but a 10th

That's not a proof by any definition of the word I understand. Imagining something does not prove the existence (or otherwise) of that thing. [edit] but a 10th century bishop writing 77 years after the end of the 10th century is still noteworthy :o)