When Bilbo does "the whimper."
Oh, and when Thorin rolls his eyes and kicks the dwarves when he realizes what Bilbo's trying to do.
Bilbo's speech at the end:
"Look, I know you doubt me. I know you always have. And you're right, I often think of Bag End. I miss my books. And my armchair, and my garden. See, that's where I belong--that's home. And that's why I came back, because…you don't have one. A home. It was taken from you. But I will help you take it back, if I can."
And Gandalf's little soliloquy:
"Saruman believes it is only great power that can hold evil in check, but that is not what I have found. I have found it's in the small things--everyday deeds of ordinary folk that keeps the darkness at bay. Simple acts of kindness, and love. Why Bilbo Baggins? Perhaps it is because I am afraid--and he gives me courage."