The writer of the criticism never suggested the idea that he himself, having been fully provided with books of reference, and having learned the art of finding in them what he wanted at a moment's notice, had, as he went on with his work, checked off the blunders without any more permanent knowledge of his own than a housekeeper has of coals when she counts so many sacks into the coal-cellar. He spoke of the parentage of one wicked ancient lady, and the dates of the frailties of another, with an assurance intended to show that an exact knowledge of all these details abided with him always. 
He checked off the blunders with an assurance intended to show that he himself had an exact knowledge of all these details.
