Final answer:
Justice Potter Stewart confessed that 'I know it when I see it' concerning his test for obscenity in a famous Supreme Court case.
Step-by-step explanation:
Justice Potter Stewart famously confessed, "I know it when I see it", regarding his threshold test for obscenity in Jacobellis v. Ohio (1964). This statement was made in a concurring opinion wherein Stewart struggled to define hard-core obscenity, but knew that it was not present in the film under review. The phrase has since become one of the most famous quotes in the Supreme Court lexicon, encapsulating the recognizably intuitive nature of certain legal judgments.
The provided text from the exchange between Socrates and a prisoner in Plato's Allegory of the Cave illustrates the idea of enlightenment and the difficulty of adjusting to new truths when released from a state of ignorance. Though while interesting, it does not directly relate to Justice Stewart's confession.