What has just been said about the attitude of modern critics toward Diodorus must not be taken to imply that this earliest of great world historians has, on the whole, failed of an appreciative audience. The facts of the case amply refute such a supposition as this. An author writes to be read, and in the last resort the only valid criterion as to the value of his work is found in the preservation or neglect of that work by successive generations of readers.
Tested by this standard, very few of the ancient writers have obtained such a measure of appreciation as has been accorded to Diodorus. Something like three-fourths of what he wrote has been lost, it is true; but in fairly estimating the import of this, one must consider the bulk of what remains. The briefest comparison supplies us with some very interesting data. It appears that, of the entire series of the predecessors of Diodorus, no single historian has left us anything like a comparable bulk of extant matter. Only one predecessor in any field of literature, namely, Aristotle, greatly exceeds him in this regard, and a single other writer, Plato, about equals him. Turning to the contemporaries of Diodorus and to his successors in the use of the Greek language, a similar result is shown. A single writer exceeds him in output. This is Plutarch, the biographer and philosopher rather than historian proper. No other Greek writer in any field equals Diodorus, though two historians, Dion Cassius and Dionysius of Halicarnassus, are within hailing distance. When one reflects on the actual labour implied by the preservation of any manuscript throughout the long generations of the middle ages, these data speak volumes for the aggregate judgment passed upon the work of Diodorus by posterity. Of the long list of Greek historians,—a list mounting far into the hundreds, as proved by fragmentary remains,—only three as ancient as Diodorus have fared better than he, these three being Herodotus, Thucydides, and Xenophon. But the entire bulk of the works of these three writers does not so very greatly exceed the bulk of the extant writings of Diodorus. The works of Herodotus and Thucydides together do not comprise more matter than is contained in books eleven to twenty of Diodorus, which are preserved en bloc.
It would, of course, be absurd to imply that the mere bulk of the manuscripts preserved before the age of printing is a test of the value of an ancient author’s work; but, on the other hand, bearing in mind always the labour employed in the production of a single copy of a large work, it would be equally absurd to deny that the bulk of manuscripts has a certain bearing upon the value of the matter which they preserve. No doubt many a scribe would be deterred from starting out to copy manuscript by the great bulk of the work, and where he had no great preference, would be influenced by this alone to choose a smaller book. Again, doubtless many a scribe wearied of his task in the case of the more ponderous works, and gave it up after copying a few books. This common-sense explanation no doubt accounts for the fact that quite generally the earlier books rather than the later ones of works that have come down to us in a fragmentary condition are the ones preserved. Had Herodotus and Thucydides written forty books instead of eight or nine, it is very unlikely that even their genius would have sufficed to preserve the entire number. The case of Livy, whose work, despite the beauty of its style, has come down to us so sadly mutilated, sufficiently sustains this supposition. It is nothing against the merit of Diodorus, then, to reflect that half his work is lost; the wonder is rather that so much of it has been preserved.
We have dwelt thus at length upon the work of Diodorus because it is a work that may be taken as in many ways representative of world histories in general. Certainly it was by far the greatest world history produced in antiquity, of the exact merits of which we have any present means of judging. Indeed, there is only one other world history that has come down to us, and this, the work of Justin, is in itself only an abridgment of the writing of another author, Trogus Pompeius. Considering when it was written, this work of Trogus, if we may judge from the abridgment, was an admirable production, and the abridgment itself is of great value in throwing light on some periods that otherwise are not well covered by extant documents. As a whole, however, it is a compendium of history rather than a comprehensive work like that of Diodorus. Of the works of the other world historians of antiquity it is impossible to speak with any measure of certainty. Polybius accredited Aphorus with being the only man who had written a world history before his day. It is known that Aphorus lived in the fifth century B.C., and that he was a fellow-pupil of another historian, Theopompus, in the famous school of Isocrates at Athens; but his work is only known to us through inadequate fragments and the indirect quotations of other authors. The same is true of the works of Theopompus just referred to, and of Timæus, another Greek whose writing had something of world historic comprehensiveness. But, even had these works been preserved, it may well be doubted whether any one of them would compare favourably with the great history of Diodorus, which must stand out for all time as the greatest illustration of the writing of world history in antiquity.
Diodorus, as we have seen, brought his work down to the time of the Gallic wars of Cæsar. There are references in his writing which imply that he lived well into the time of Augustus. He probably died not long before the beginning of the Christian era.
No Greek of later time and no Roman of any period produced a work that supplanted the history of Diodorus, though most of the Byzantine historians produced chronicles, many of which had more or less aspect of world history in epitome. Several of these have been preserved, but no one thinks of comparing them with the work of the older writer. The chronological work of Eusebius, however, deserves a word of special mention. It was a mere epitome of world history, but a relatively comprehensive one, and one which, through the loss of more pretentious works, has come to be of great value to the modern historian. It was written originally in Greek, but the most important copy of it that has come down to us is, curiously enough, an Armenian translation. It is the Latin translation of this Armenian manuscript that is the work usually referred to by modern historians in speaking of Eusebius. The encyclopædia of history compiled for Constantine Porphyrogenitus, to which reference has already been made, must also be mentioned as a world history of real importance. It was based almost exclusively upon Greek authors, who were quoted at length, with such abbreviations or modifications as were made necessary in adjusting the various texts to one another. As a means of preserving the work of numerous important Greek historians this collection had the utmost value, but, unfortunately, it has come down to us in a much mutilated condition. During the Byzantine period the minds of would-be historians of the Western world were so occupied with ecclesiastical quarrels and the chronicles of local princes, that no one thought of world histories in the broader sense. We should be thankful that here and there a monk had interest and energy enough to copy the ancient authors, and thus in part to preserve them. Considering the intellectual atmosphere of the time, the wonder is, not that so many of the pagan authors were lost, but rather that any of them were preserved. Yet there were occasional gleams of light, even in the so-called dark age. Such a one of peculiar interest to the English reader is found in the fact that King Alfred translated into Anglo-Saxon the compendious world history of Orosius, a work that otherwise would be but little known to fame, but which, thanks to its brevity of treatment, and to this very unusual distinction of translation into a “barbaric tongue,” no doubt served a most excellent purpose in giving to the Anglo-Saxons of the ninth century a glimpse of the events of ancient times.