Our knowledge of this production is derived from three sources which, taken in combination, afford a considerable amount of inform ation with regard to the nature and extent of the undertaking. 1. A few brief fragments quoted by (Pliny ?), Vopiscus, Jerome, Augustin, Orosius, Priscian, Isidorus, and others down to John of Salisbury and Matthew of Westminster. 2. The Excerpts of Just. 3. A sort of epitome found in several MSS., indicating, under the name of prologues (prologi), the contents of each chapter in regular order, bearing a close resemblance, in form and substance, to the summaries prefixed to the books of Livy, and, like these, proceeding from some unknown pen.

We thus ascertain that the original was comprised in 44 books, that the title was Liber Historiarum Philippicarum, the additional words et totius mundi origines et terrae situs, given by the author of the prologues, being in all probability an inaccurate explanation appended by himself. The term was employed because the chief object proposed was to give a complete account of the origin, rise, progress, decline, and extinction of the Macedonian monarchy, with all its branches; but in the execution of this design, Trogus permitted himself, in imitation of Herodotus and Theopompus, to indulge in so many excursions, that a very wide field of investigation was embraced, although the designation is altogether inapplicable. In the first six books, which served as a sort of introduction to the rest, while ostensibly examining into the records of the period anterior to Philip I., he took a survey of the various states which eventually became subject to, or in any way connected with, the Macedonians. In this manner the empires of the Assyrians, Medes, and Persians, were passed under review: the expedition of Cambyses against Egypt led to a delineation of that country and its people: the contest of Darius with the Scythians was accompanied by a geographical sketch of the nations which bordered on the northern and eastern shores of the Euxine: the invasion of Xerxes brought the Athenians and Thessalians on the stage, who in turn called up the Spartans and other Dorian clans. A narrative of the Peloponnesian war naturally succeeded: with the fatal expedition to Sicily was interwoven a description of that famous island, of its races, and of the colonies spread over its surface. The downfall of Athens was next recorded, followed by the enterprise of the younger Cyrus, the campaigns of Agesilaus in Asia, and various minor events, until the decay of the Lacedemonian and the rise of the Boeotian influence gradually introduced the history of Macedon, which, commencing with the seventh book, was continued down to the ruin of Perseus and the abortive attempt of the impostor Andriscus, which were detailed in the thirty-third. But even after the main subject had been fairly commenced, it could only be regarded in the same light as the argument of an Epic poem, which admits of continual episodes and digressions--the guiding-thread of the discourse, which, although often apparently lost, forms the connecting links by which the various portions of the complicated fabric are united and held together in one piece. Thus the interference of Philip in the affairs of Greece suggested an exposition of the causes which led to the Sacred War: his attacks upon Perinthus and Byzantium involved a disquisition on the early fortunes of the cities in question: his dispute with the Scythians and his relations with the Persians afforded an apology for resuming the chronicles of these nations: the transactions of Artaxerxes Mnemon produced an account of the Cyprians and Paphlagonians, while the exploits of Alexander the Epirotan furnished a pretext for an essay on the Apulians, Sabines, and Samnites. The strife which arose among the successors of Alexander the Great formed in itself an almost inexhaustible theme, while the ambitious schemes of Pyrrhus were illustrated by a dissertation on the Sicilians and Carthaginians, which occupied no less than six books. After the reduction of Macedonia to a Roman province, with which, as we have seen above, the thirty-third book closed, the following nine were devoted to the affairs of Asia, Pontus, Syria, Egypt, and Boeotia, including the Parthian monarchy; the forty-second and forty-third contained a sketch of the steps by which the Romans had attained to supremacy; and in the last were collected some scattered notices in reference to the Ligurians, Massilians, and Spaniards, the Greeks having been previously (lib. xxiv.) discussed.

To what period Justin (who is designated in one MS. as Justinus Frontinus, and in another as M. Junianus Justinus, while the great majority exhibit the simple appellation Justinus) belongs it is impossible to determine with certainty. The expression which he employs (8.4.7), " Graeciam etiam nunc et viribus et dignitate orbis terrarum principem" would in itself be scarcely sufficient to prove that he flourished under the Eastern emperors, even if it related to the age in which he composed, and not, as it does in reality, to the particular epoch of which he happened to be treating in his narrative; while the words " Imperator Antonine," which appear in the preface, are to be found in no MS. now extant, but are probably an interpolation foisted in by some of the earlier editors who followed Isidorus, Jornandes, and John of Salisbury, in confounding Justin the historian with Justin the Christian father and martyr. The earliest writer by whom he is mentioned is Saint Jerome (Prooem. in Daniel), and therefore he cannot, at all events, be later than the beginning of the fifth century.

We must not omit to remark that the quotations from Trogus found in Pliny appear to be all taken from a treatise De Animalibus mentioned by Charisius (p. 79. ed. Putsch.), and not from his histories.