Gandalf: "Well, why does it matter? He's back!"
Thorin: "It matters. I want to know - why did you come back?"
Bilbo: "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. That's why I came back... 'cause you don't have one, a home. It was taken from you. But I will help you take it back if I can."