"The portrait Carlyle has drawn of Cagliostro is the one most familiar to English readers. Now, though Carlyle's judgments have in the main been upheld by the latest historians (who have had the advantage of information to which he was denied access), nevertheless, like everybody else, he made mistakes. In his case, however, these mistakes were inexcusable, for they were due, not to the lack of data, but to the strong prejudices by which he suffered himself to be swayed to the exclusion of that honesty and fairness he deemed so essential to the historian."