I wondered what it was that he was such a quick judge of.

I have thought of it many times since, and still wondered what it could be.

He and I talked it over, but could not guess it out.

He thought it must be fox-hounds or horses, for he is a good judge of those--no one is a better.

But you couldn't know that, because you didn't know him; you had mistaken him for some one else; it must be that, he said, because he knew you had never met him before.