Parmegianni, Giovanni. 2014. Between Thucydides and Polybius: The Golden Age of Greek Historiography. Hellenic Studies Series 64. Washington, DC: Center for Hellenic Studies. http://nrs.harvard.edu/urn-3:hul.ebook:CHS_ParmegianniG_ed.Between_Thucydides_and_Polybius.2014.
8. Ephorus, Polybius, and τὰ καθόλου γράφειν: Why and How to Read Ephorus and his Role in Greek Historiography without Reference to ‘Universal History’ 
1. ‘Universal History’ in Greek Historiography
2. Ephorus and his ‘Cover-Texts’
3. ‘Universal History’ Deconstructed
Polybius’ statement hinges on the equivalence between his history and Ephorus’ history: they both make the same boast (τὴν αὐτὴν φωνήν), that is, τὰ καθόλου γράφειν. Nevertheless, this fundamental correspondence has been queried, because, as Polybius frequently reminds us, his history involves explaining
This master narrative only covers just over one hundred years, 264-146, even including the preliminary material covered in Polybius’ first two books (the προκατασκευή), and the extension to include events down to the aftermath of the sack of Corinth in 146. That Polybius’ own chronological coverage is so narrow has caused concern about how Polybius could equate his history with Ephorus’ work, which covered, on modern ‘calculations’, approximately 750 years. 
4. Diodorus and ‘Universal History’
Diodorus’ evaluations of his predecessors can be read as explanations of how his predecessors failed to write ‘Universal History’, because the ideal of history presented by Diodorus and manifested in his work insofar as it survives equates to the modern notion of ‘Universal History’: by Diodorus’ logic and utilitarian purpose, the best history was one that involved the most exempla, and so the broadest chronological and geographical range. Nevertheless, there is one crucial difference: Diodorus had no notion of such a project as a separate genre or type of historiography: it was the pinnacle of the entire historiographical enterprise. This ideal was also represented by Diodorus’ history alone: from Diodorus’ perspective, there was no other ‘Universal History’. This was not a generic argument, but much more self-serving, emphasising how Diodorus’ history was necessarily unsurpassed and unsurpassable as an example of historical narrative as a whole: all other histories were ultimately failed attempts to achieve what Diodorus’ history embodied.
In this passage, Diodorus is using Ephorus’ work as an example of his point that writers of great reputation had only discussed “the more recent events” (τὰς δὲ νεωτέρας πράξεις). For Diodorus nonetheless to be calling Ephorus’ subject a ‘Universal History’ when he refers to Ephorus as ὑποστησάμενος γράφειν τὰς κοινὰς πράξεις would be highly paradoxical. The rhetorical thrust of this passage is precisely the reverse!
There is no suggestion here that Ephorus’ history marked a radical departure from Herodotus’ practice; quite the reverse. Where Ephorus’ history had started in Diodorus’ eyes with the return of the Heraclidae, Herodotus’ work commenced still earlier: before the Trojan War. Given Herodotus’ ultimate focus on the wars of 481–479, Diodorus’ description of Herodotus’ history may seem paradoxical, but it would be unwise to dismiss it as somehow invalid.  Diodorus is in good company: his approach is in keeping both with the prologue Herodotus wrote to his own work, and the description offered of Herodotus’ history by Dionysius of Halicarnassus. Herodotus wrote his history
According to Dionysius,
It would perhaps be unwise to place too much weight on Dionysius’ quotation of just the first half of Herodotus’ self-description, excluding mention of the cause of the war. Nevertheless, the emphasis of these descriptions reminds us how different ancient perceptions of even famous works we think we know well may have been.  They also support Diodorus’ emphasis on continuity between Ephorus and Herodotus: it is not self-evident that Diodorus’ and Dionysius’ descriptions of Herodotus and Ephorus show an active concern for genre, let alone that they mask an awareness of a significant shift in historiographical approach in the fourth century that could elsewhere have been conceived as equating to a different genre. Development and evolution, not disjunction and revolution, best summarise their approach to Ephorus and his position in the wider historiographical tradition. 
5. Polybius and ‘Universal History’
Here, Polybius does not envisage confusion arising because the viewer has overlooked a physical part of the animal. Instead, the difficulty arises because of the way the parts are arranged: they are διερριμμένα, dissevered, and so are seen in isolation from each other. Though the man may fancy he is able to conjure up a picture of the animal as it is when whole, in fact, he cannot, and realizes this when he does see the animal whole.
On the second analysis above, wherein writing καθόλου and κατὰ μέρος are complementary, these statements make perfect sense: Polybius is ostentatiously emphasizing his mastery of the historical discipline, both in narrating his overall theme, and with reference to each individual event mentioned. This approach is also entirely consistent with his use of καθόλου and κατὰ μέρος in the passages discussed above. By contrast, those who insist with Jacoby on a generic approach, that τὰ καθόλου elsewhere means ‘Universal History’, and that it is to be contrasted with accounts written κατὰ μέρος, which “clearly implies individual works on small topics, or monographs,” have more difficulty. Even though Sacks, in discussing this passage, acknowledges that “[k]atholou must mean something like ‘the general import’ and kata meros ‘particulars,’ or ‘details’,” this does not cause him to question his previous conclusions regarding the meaning of τὰ καθόλου and κατὰ μέρος. Instead, it is “especially vexing” that Polybius could write so “offhandedly” in stating that he writes both καθόλου καὶ κατὰ μέρος.  On occasion, non liquet is an appropriate answer; authors can be self-contradictory. To suggest offhandedness when dealing with programmatic passages at significant locations in a work is, however, less than satisfying, especially when there is a clear, logical alternative: that Polybius is not concerned with genre, and even less with ‘Universal History’.
6. Ephorus without ‘Universal History’
7. Polybius and Ephorus
8. ‘Universal History’ without Ephorus