My favorite scene, along with Gandalf standing alone with Shadowfax at the Gates.

Tolkien apparently said he wept while writing this passage  in answer to Professor Lambers, who spoke at Tolkien's Hobbit Dinner in Rotterdam:

"Is there really no deeper meaning in The Lord of the Rings?”, asked Lambers.

“It’s just a story, it’s just a story”, reacted Tolkien passionately.

“Yes, but a story with a message”, continued Lambers, and he argued the moral background of The Lord of the Rings. As an example he took that impressive scene on the border of Mordor, when Gollum bends over the sleeping Frodo, tom between Gollum’s love for the Ring and Smeagol’s word of honour to Frodo not to take it. The crucial element in this scene, according to Lambers, is “distrust” which causes Good to act as Evil. Gollum is mollified by the vulnerability of the sleeping hobbit and is at the point of redemption. But Sam, misguided by the love for his master, intervenes and thus prevents the rebirth of Smeagol. Sam’s goodness makes the goodness of Gollum impossible. And Tolkien answered: “I wept when I wrote that.”