Leptines); De regno (i.–iv.), addressed to Trajan, a eulogy of the monarchical form of government, under which the emperor is the representative of Zeus upon earth; De Aeschylo et Sophocle et Euripide (lii.), a comparison of the treatment of the story of Philoctetes by the three great Greek tragedians; and Philoctetes (lix.), a summary of the prologue to the lost play by Euripides. In his later life, Dio, who had originally attacked the philosophers, himself became a convert to Stoicism. To this period belong the essays on moral subjects, such as the denunciation of various cities (Tarsus, Alexandria) for their immorality. Most pleasing of all is the Euboica (vii.), a description of the simple life of the herdsmen and huntsmen of Euboea as contrasted with that of the inhabitants of the towns. Troica (xi.), an attempt to prove to the inhabitants of Ilium that Homer was a liar and that Troy was never taken, is a good example of a sophistical rhetorical exercise. Amongst his lost works were attacks on philosophers and Domitian, and Getica (wrongly attributed to Dio Cassius by Suïdas), an account of the manners and customs of the Getae, for which he had collected material on the spot during his banishment. The style of Dio, who took Plato and Xenophon especially as his models, is pure and refined, and on the whole free from rhetorical exaggeration. With Plutarch he played an important part in the revival of Greek literature at the end of the 1st century of the Christian era.
Editions: J. J. Reiske (Leipzig, 1784); A. Emperius (Brunswick, 1844); L. Dindorf (Leipzig, 1857), H. von Arnim (Berlin, 1893–1896). The ancient authorities for his life are Philostratus, Vit. Soph. i. 7; Photius, Bibliotheca, cod. 209; Suidas, s.v.; Synesius, Δίων. On Dio generally see H. von Arnim, Leben und Werke des Dion von Prusa (Berlin, 1898); C. Martha, Les Moralistes sous l’empire romain (1865); W. Christ, Geschichte der griechischen Litteratur (1898), § 520; J. E. Sandys, History of Classical Scholarship (2nd ed., 1906); W. Schmid in Pauly-Wissowa’s Realencyclopädie, v. pt. 1 (1905). The Euboica has been abridged by J. P. Mahaffy in The Greek World under Roman Sway (1890), and there is a translation of Select Essays by Gilbert Wakefield (1800).
DIOCLETIAN (Gaius Aurelius Valerius Diocletianus) (A.D. 245–313), Roman emperor 284–305, is said to have been born at Dioclea, near Salona, in Dalmatia. His original name was Diocles. Of humble origin, he served with high distinction and held important military commands under the emperors Probus and Aurelian, and accompanied Carus to the Persian War. After the death of Numerianus he was chosen emperor by the troops at Chalcedon, on the 17th of September 284, and slew with his own hands Arrius Aper, the praefect of the praetorians. He thus fulfilled the prediction of a druidess of Gaul, that he would mount a throne as soon as he had slain a wild boar (aper). Having been installed at Nicomedia, he received general acknowledgment after the murder of Carinus. In consequence of the rising of the Bagaudae in Gaul, and the threatening attitude of the German peoples on the Rhine, he appointed Maximian Augustus in 286; and, in view of further dangers and disturbances in the empire, proclaimed Constantius Chlorus and Galerius Caesars in 293. Each of the four rulers was placed at a separate capital—Nicomedia, Mediolanum (Milan), Augusta Trevirorum (Trier), Sirmium. This amounted to an entirely new organization of the empire, on a plan commensurate with the work of government which it now had to carry on. At the age of fifty-nine, exhausted with labour, Diocletian abdicated his sovereignty on the 1st of May 305, and retired to Salona, where he died eight years afterwards (others give 316 as the year of his death). The end of his reign was memorable for the persecution of the Christians. In defence of this it may be urged that he hoped to strengthen the empire by reviving the old religion, and that the church as an independent state over whose inner life at least he possessed no influence, appeared to be a standing menace to his authority. Under Diocletian the senate became a political nonentity, the last traces of republican institutions disappeared, and were replaced by an absolute monarchy approaching to despotism. He wore the royal diadem, assumed the title of lord, and introduced a complicated system of ceremonial and etiquette, borrowed from the East, in order to surround the monarchy and its representative with mysterious sanctity. But at the same time he devoted his energies to the improvement of the administration of the empire; he reformed the standard of coinage, fixed the price of provisions and other necessaries of daily life, remitted the tax upon inheritances and manumissions, abolished various monopolies, repressed corruption and encouraged trade. In addition, he adorned the city with numerous buildings, such as the thermae, of which extensive remains are still standing (Aurelius Victor, De Caesaribus, 39; Eutropius ix. 13; Zonaras xii. 31).
See A. Vogel, Der Kaiser Diocletian (Gotha, 1857), a short sketch, with notes on the authorities; T. Preuss, Kaiser Diocletian und seine Zeit (Leipzig, 1869); V. Casagrandi, Diocleziano (Faenza, 1876); H. Schiller, Gesch. der römischen Kaiserzeit, ii. (1887); T. Bernhardt, Geschichte Roms von Valerian bis zu Diocletians Tod (1867); A. J. Mason, The Persecution of Diocletian (1876); P. Allard, La Persécution de Dioclétien (1890); V. Schultze in Herzog-Hauck’s Realencyklopädie für protestantische Theologie, iv. (1898); Gibbon. Decline and Fall, chaps. 13 and 16; A. W. Hunzinger, Die Diocletianische Staatsreform (1899); O. Seeck, “Die Schatzungsordnung Diocletians” in Zeitschrift für Social- und Wirthschaftsgeschichte (1896), a valuable paper with notes containing references to sources; and O. Seeck, Geschichte des Untergangs der antiken Welt, vol. i. cap. 1. On his military reforms see T. Mommsen in Hermes, xxiv., and on his tariff system, Diocletian, Edict of.
DIOCLETIAN, EDICT OF (De pretiis rerum venalium), an imperial edict promulgated in A.D. 301, fixing a maximum price for provisions and other articles of commerce, and a maximum rate of wages. Incomplete copies of it have been discovered at various times in various places, the first (in Greek and Latin) in 1709, at Stratonicea in Caria, by W. Sherard, British consul at Smyrna, containing the preamble and the beginning of the tables down to No. 403. This partial copy was completed by W. Bankes in 1817. A second fragment (now in the museum at Aix in Provence) was brought from Egypt in 1809; it supplements the preamble by specifying the titles of the emperors and Caesars and the number of times they had held them, whereby the date of publication can be accurately determined. For other fragments and their localities see Corpus Inscriptionum Latinarum (iii., 1873, pp. 801 and 1055; and supplement i, 1893, p. 1909); special mention may be made of those of Elatea, Plataea and Megalopolis. Latin being the official language all over the empire, there was no official Greek translation (except for Greece proper), as is shown by the variations in those portions of the text of which more than one Greek version is extant. Further, all the fragments come from the provinces which were under the jurisdiction of Diocletian, from which it is argued that the edict was only published in the eastern portion of the empire; certainly the phrase universo orbi in the preamble is against this, but the words may merely be an exaggerated description of Diocletian’s special provinces, and if it had been published in the western portion as well, it is curious that no traces have been found of it. The articles mentioned in the edict, which is chiefly interesting as giving their relative values at the time, include cereals, wine, oil, meat, vegetables, fruits, skins, leather, furs, foot-gear, timber, carpets, articles of dress, and the wages range from the ordinary labourer to the professional advocate. The unit of money was the denarius, not the silver, but a copper coin introduced by Diocletian, of which the value has been fixed approximately at 15th of a penny. The punishment for exceeding the prices fixed was death or deportation. The edict was a well-intended but abortive attempt, in great measure in the interests of the soldiers, to meet the distress caused by several bad harvests and commercial speculation. The actual effect was disastrous: the restrictions thus placed upon commercial freedom brought about a disturbance of the food supply in non-productive countries, many traders were ruined, and the edict soon fell into abeyance.
See Lactantius, De mortibus persecutorum, vii., a contemporary who, as a Christian, writes with natural bias against Diocletian; T. Mommsen, Das Edict Diocletians (1851); W. M. Leake, An Edict of Diocletian (1826); W. H. Waddington, L’Édit de Dioclétien (1864), and E. Lépaulle, L’Édit de maximum (1886), both containing introductions and ample notes; J. C. Rolfe and F. B. Tarbell in Papers of the American School of Classical Studies at Athens, v. (1892) (Plataea); W. Loring in Journal of Hellenic Studies, xi. (1890) (Megalopolis); P. Paris in Bulletin de correspondance hellénique, ix. (1885) (Elatea). There is an edition of the whole by Mommsen, with notes by H. Blümner (1893).
