The quote from Jodi Picoult's "The Tenth Circle" reflects a deep sense of loss associated with the end of innocence and imagination. It suggests that the day someone stops pretending or dreaming is a profoundly sad moment. This implies that the act of pretending is a vital part of life, allowing individuals to escape reality and embrace creativity, even if just for a moment.

This sentiment highlights the importance of imagination and how it shapes our experiences. When a person ceases to engage in pretense, it may indicate a loss of hope or joy, leading to a more mundane existence. Thus, this quote serves as a reminder to cherish those moments of pretense and creativity, as they enrich our lives and help us cope with reality.