Aang (enraged): How could you let them take Appa? Why didn't you stop them?
Toph: I couldn't! The library was sinking! You guys were still inside and—
Aang: You could have come to get us! I could have saved him!
Toph: I can hardly feel any vibrations out here. The sandbenders snuck up on me and there wasn't time for—
Aang: You just didn't care! You never liked Appa! You wanted him gone!