“I must find the Mountain of Fire and cast the thing into the gulf of Doom. Gandalf said so. I do not think I shall ever get there.”
This quote is full of pathos. Sam has just accidentally let the matter of the Ring drop to Faramir, and it’s like Frodo sags from weariness. Tolkien doesn’t describe it, but you can see his shoulders drooping. “Gandalf said so,” he states flatly, like a child who is doing what it’s told; “I do not think I shall ever get there.” The word choice is perfection here. Instead of the less impactful “don’t”, Frodo pronounces each word, “I do not think”: resigned, unhopeful. I would argue this is one of the best lines of the book.