The World History of Diodorus ends with the era under Octavian in Diodorus' own lifetime. However, of the 40 books only the first half is complete, the second half, the period from 301 B.C., extant only in fragments from the Byzantine period (Photios, Constantinian Excerpts, Tzetzes). Therefore little is revealed about Diodorus' intentions, his interpretation of his present through the past or his relationship to his own work, which would only be clear from these later sections. Despite this, comparisons with parallel testimonies and characteristics of the language, as well as the interpretation of some chance extant passages suggest that Diodorus' portrayal of the period in question, beginning in the earliest known reaches of history, culminated, so to speak, in the history of Rome. Thus, the origins and the developmental process were not only historical, but even more, they were ethical, the conclusion being the right of Rome to its empire as well as its role as the eliminator of barbarity and the educator of better ways of life. This would determine the next period of the world's history, which naturally followed the unified history as presented by Diodorus. At the same time it seemed to Diodorus that the period from the end of the Diadochen until the triumph of the empire was accompanied in all areas of life by a development that could lead to disaster, not to a small extent caused by the interrelations of heterogeneous segments like the Hellenistic world, which also could not be explained purely politically. The power of Rome's own authority to stem this process is, nonetheless, still another aspect proving its worth.
