Katara, do you remember what I told you-- about having two eyelids?

For this to work, you're going to need to close that second eyelid. [there are no dips or rises in his tone, he speaks as if he's explaining how to swim]

Every living thing could do it, at one time. So all it will take is remembering. [here, he sets aside the unrelenting pricks of doubt and skepticism-- in favor of a confidence that there are some things that are the same in every world. After all, some people could see the River here. Others could not.]