Her face was her chaperone.

The epigram suggests a woman whose appearance—whether through beauty, severity, innocence, or an unmistakable air of propriety—functions as a social safeguard. In a culture where a “chaperone” was meant to protect a woman’s reputation and regulate access to her, the line implies that her face alone discourages impropriety or unwanted advances, making external supervision unnecessary. The wit depends on social codes of respectability: physiognomy becomes a proxy for moral authority and social protection. Depending on narrative tone, it can read as compliment (dignity that commands respect) or as barbed humor (a forbidding face that keeps suitors away).