Imitation, or mimesis, is inherently ambiguous -- if not, it wouldn't be imitation. But the relation of copy to original can be difficult to decide, and the legendary tales of trompe l'oeil works of the Greek painters dramatize the element of cheat, of trickery:
Zeuxis and his contemporary Parrhasius (of Ephesus and later Athens) are reported in the Naturalis Historia of Pliny the Elder to have staged a contest to determine which of the two was the greater artist. When Zeuxis unveiled his painting of grapes, they appeared so luscious and inviting that birds flew down from the sky to peck at them. Zeuxis then asked Parrhasius to pull aside the curtain from his painting, only for Parrhasius to reveal the curtain itself was a painting, and Zeuxis was forced to concede defeat. Zeuxis is rumoured to have said: 'I have deceived the birds, but Parrhasius has deceived Zeuxis.'Interesting that much of Zeuxis' work ended up in Rome, where Ovid certainly would have seen it - and also noteworthy that one famous subject of the artist was Marsyas.
Our lively discussion of Athena vs. Arachne today was, in a very real sense, provoked by the way Ovid designs his tale, his argumentum. Ovid calls the stories depicted in the webs of his contestants the vetus argumentum for a reason -- not only will they be submitted to be judged in the contest (certamen <- cerno), they are also arguments about the nature of art and its relation to nature, to inspiration, and to the divine.
To judge an argument critically, it must be sifted, discerned, tested. The root of argument is arguo, which means prove, or assert, but that sense quickly slides into "reprove, accuse, blame, censure, denounce." The root rests uneasily on the creaky fence that divides the certitude of rational and evidentiary processes such as science and logic on the one hand from the vitriol-charged rhetoric of prosecutorial denunciation on the other.
The discussion surrounding Athena and Arachne has many elements, ambiguities, and angles, because Ovid refuses to let the contest remain simply within what we normally think of as "aesthetics" -- i.e., whether something is beautiful, and if we compare two works, which is moreso. The contest here is between Wisdom's ars and that of a mortal girl. The harrowing ambiguities in the way it plays out -- the ire of Athena and disfiguration of Arachne -- are not easily "settled" by some neat allocation of good vs. evil.
What is clear from the tale, as well as others in Book 6, is that ambiguities can be harrowing, and Wisdom is not always tolerant. The book begins with Athena being reminded by the tale of the Muses in Book 5 of iustam iram - "rightful wrath" (Golding's translation). We certainly witness her iram towards Arachne. The question that the violence in the tale compels us to decide is whether we are dealing with a wise intolerance, or a most intolerant Wisdom.