To err is human, to purr is feline.

A playful twist on the well-known proverb “To err is human” (often linked to Alexander Pope), Byrne’s line replaces moral gravity with a cat-centered punchline. The humor depends on near-rhyme (err/purr) and on the sudden shift from universal human fallibility to a specific animal trait. In doing so, it gently mocks our tendency to dress ordinary truths in solemn aphorisms: if humans are defined by mistakes, cats—by contrast—are defined by contentment and self-possession, signaled by purring. The quip also works as affectionate anthropomorphism, suggesting that every species has its characteristic “default setting,” and that not all defining traits are tragic or profound.