“This sentence is not true”

He had her attention now. Her big eyes grew even bigger as she contemplated the contradiction. Either the sentence was true, in which case it was a lie, which made it true again. Or it was false, which made it true, which made it false again. This was too much to take in at once, the collapse of categories into an infinite regression from which there was no escape. Truth is meaningless now, and –

She meowed disinterestedly, and went to find another napping spot. One without philosophers waking her up with strange mouth noises