I shall begin with a definition. I am dealing with ‘secular historians,’ and thus I am excluding ecclesiastical history, and chronography. The second of these two genres, chronography, continued a tradition which goes back as far as Thucydides' contemporary, Hellanicus, but under a Christian empire it acquired a Christian bias and dropped any pretence of literary style. ‘Ecclesiastical history,’ which, as far as we know, was invented by Eusebius of Caesarea, and displays a somewhat unclassical passion for documentation, dealt with the church and history as it affected the church. Its presuppositions about historical causation were Christian. The secular historians, on the other hand, continued the classical traditions of historiography begun by Herodotus and Thucydides, and their subject matter was war and politics, and the cross between the two, which was diplomacy.