In the fairy tale
Beauty and the Beast, the story begins where a young prince refuses to shelter what appears to be an old beggar woman, only to discover that she is not what she seems.
On September 19, TA 3018, Tolkien uses this same story device when he has Gandalf arrive at Edoras seeking the aid of the King of Rohan on the wings of the magnificent Gwaihir...yet knocks on the door of the Golden Hall and is turned away because he is perceived to be a beggar. Even though it is obvious that Gandalf has visited Edoras before, he is unrecognized and refused entry, thus delaying his flight to the Shire where Frodo frets over his whereabouts and seems to sense his impending peril.
The Enemy is moving and Gandalf is ignored in Rohan.
Artwork: "Edoras" by Alan Lee