This book ends with a picture that the narrator calls “the loveliest and saddest landscape in the world” (Epilogue.1) – this is the spot on the Earth where the little prince landed and then disappeared.
He urges us to get really familiar with the landscape. That way, if we ever pass by it, we’ll know it. And, if the prince shows up there, we’ll know him, too.
And if we ever meet the little prince, the narrator asks us to send him word that the prince has come back.