Here he looks at an iconic figure from the Middle Ages from a new perspective, criticizing the views of the famous German historian Ernst Kantorowicz concerning Frederick II of Hohenstaufen, whom Abulafia sees as a conservative figure rather than as a genius born out of his time.
The author is analyzing a well-known historical figure from the Middle Ages and offering a different interpretation than that of a famous historian.  Abulafia's view differs from Kantorowicz's assessment of Frederick II of Hohenstaufen.