The place isn't patronized much, and it shuts up at eight.

You and I can go there and have dinner at six, say, and watch for them to come." Then they set to work at their letters.
"Now," said Condy, "we must have these sound perfectly natural, because if either of these people smell the smallest kind of a rat, you won't catch 'em.

You must write not as YOU would write, but as you think THEY would.

This is an art, a kind of fiction, don't you see?
We must imagine a certain character, and write a letter consistent with that character.

Then it'll sound natural.