Why has montag foolish to use the phrase once upon a time?

Montag's use of the phrase "once upon a time" is foolish because it evokes a sense of nostalgia and fairy-tale innocence, which contrasts sharply with the grim reality of his dystopian society. This phrase suggests a longing for a past filled with meaning and stories, highlighting the emptiness of his current existence. In a world where books are banned and critical thinking is suppressed, such a whimsical reference underscores his internal conflict and the absurdity of clinging to hope in a culture that values superficiality over depth.