"Just what I say. Old Berial thinks he's got the only screw-driver."
"But you know that there is another?"
"Who says so? I don't know anything of the sort."
"Why, then, do you cast a doubt upon the matter by saying that Mr. Berial thinks he has the only one?"
"Because I do doubt it, that's all."
"Why do you doubt it?"
"Oh, I don't know. A fellow can't always account for what he thinks, can he?"
"You must have some reason for thinking there may be a duplicate of that screw-driver."
"Well, what if I have?"
"I would like to know it."