DTOCLES. drito, who wrote vepl trvpiojv, according to Eutooius who has cited from that book {Comm. in ,Sph. ft CjfcL Archinu lib. ii. prop, v.) his method of divid- ing a sphere by a phine in a given ratio. liiit he is l>etter known by another extract which Ku- tocius {Op. Cit. lib. ii. prop, ii.) has preserved, giving his mode of solving the problem of two mean proportionals by aid of a curve, which has since been called the cissovl, and is too well known to geometers to need description, [A. De M.] DrOCLES CARYSTIUS (Ajo/c^tj? o Kapurr- Tios), a very celebnited Greek physician, was born at Carystus in Euboea, and lived in the fourth century B.C., not long after the time of Hippocrates, to whom Pliny says he was next in age and fame. {IT. N. xxvi. 6.) lie belonged to the medical sect of the Dogmatici (Gal. de Aliment. Facult. i. 1, vol. vi. p. 455), and wrote several medical works, of which only the titles and some fragments remain, preserved by Galen, Caelius Aurelianus, Oribasius, and other ancient writers. The longest of these is a letter to king Antigonus, entitled 'Eirto-roA.?) Upo(pvaKTiKri, " A Letter on Preserving Health," which is inserted by Paulus Aegineta at the end of the first book of his medical work, and which, if genuine, wa» probably addressed to Antigonus Gonatas, king of Macedonia, who died B. c. 239, at the age of eighty, after a reign of forty-four years. It resembles in its subject matter several other similar letters ascribed to Hippocrates (see Ermerins, Anecd. Med. Graeca, praef. p. xiv.), and treats of the diet fitted for the differ- ent seasons of the year. It is published in the various editions of Paulus Aegineta, and also in several other works : e. g. in Greek in Matthaei's edition of Rufus Ephesius, Mosquae, 1806, 8vo.; in Greek and Latin in the twelfth volume of the old edition of Fabricius, Dillioth. Graeca ; and in Mich. Neander's Syllogae Fhysicae., Lips. 1591, 8vo. ; and in Latin with Alexander Trallianus, Ba- sil. 1541, fol; and Meletius, Venet. 1552, 4to. &c. There is also a German translation by Hieronymus Rock, in J. Dryander's PruciicirbucJdein, Frank- fort, 1551, Bvo. Some persons have attributed to Diocles the honour of first explaining the difference between the veins and arteries ; but this does not seem to be correct, nor is any great discovery con- nected with his name. Further information re- specting him may be found in the different histories of medicine, and also in Fabricius, Bihlioth. Graeca, vol. xii. p. 584, ed. vet. ; A. Rivinus, Programma de Diocle Carystio,, Lips. 1655, 4to.; C. G. Gruner, liibliothek der Alien Aerzte, Leipz. 1781, 8vo. vol. ii. p. 605 ; C G. Kiihn, Opuscida Acad^m. Med. et riulolog. Lips. 1 827, Bvo. vol. ii. p. 87. In these works are quoted most of the passages in ancient authors referring to Diocles ; he is also mentioned by Soranus, de Arte Obsteir. pp. 15, 16, 67, 99, 124, 210, 257, 265; and in Cramer's ^««(y/. Graeca Paris, vol. i. p. 394, and vol. iv. p. 196. [W. A.G.] DI'OCLES, JULIUS ('lowAios Aio/cXtjs), of Carystus, the author of four epigrams in the Greek Anthology. (Brunck, ylna/. ii. 182; Jacobs, ii. 167.) His name implies that he was a Greek, and had obtained the Roman civitas. Reiske sup- posed him to be the same person as the rhetorician Diocles of Carystus, who is often mentioned by i>eneca. Others suppose him to be the same as the physician. The name of the poet himself is variously written in the titles to his epigrams. (Jacobs, xiii. 882, 883.) [P. «•] DIOCLETIANUS. 101! DTOCLETIA'NUS VALF/RIUS, was bom near Salona in Dalmatia, in the ye.ar a. d. 245, of most obscure parentage; his father, according to the accounts commonly received, which are, how- ever, evidently hostile, having been a freedman and provincial scribe, while the future emperor himself was indebted for liberty to a senator Anulinus. Were this last statement true ho must have been bom while his parent was a slave ; but this is impossible, for, as Niebuhr has pointed out, the Roman law, even as it stood at that period, would have prevented the son from being enlisted in the legion. From his mother, Doclea, or Dioclea, who received her designation from the village where she dwelt, he inherited the appella- tion of Docks or Diocles, which, after his assump- tion of the purple, was Latinized and expanded into the more majestic and sonorous Diocletianus, and attached as a cognomen to the high patrician name of Valerius. Having entered the army he served with high reputation, passed through vari- ous subordinate grades, was appointed to most im- portant commands under Probus and Aurelian, in process of time was elevated to the rank of consul sufFectus, followed Cams to the Persian war, and, after the death of that emperor on the banks of the Tigris [Carus], remained attached to the court dur- ing the retreat in the honourable capacity of chief captain of the palace guards {doinestici). When the fate of Numerianus became known, the troops who had met in solemn assembly at Chalcedon, for the purpose of nominating a successor, declared with one voice that the man most worthy of the sovereign power was Diocletian, who, having ac- cepted the preferred dignity, signalized his acces- sion by slaying with his own hands Arrius Aper praefect of the praetorians, who was arraigned of the murder of the deceased prince, his son-in-law [Numerianus]. The proceedings upon this occasion were characterised by an intemperate haste, which gave plausibility to the report, that the avenger of Numerian, notwithstanding his solemn protestations of innocence and disinter- ested zeal, was less eager to satisfy the demands of justice than to avert suspicion from himself and to remove a fonnidable rival, especially since he did not scruple to confess that he had long anxi- ously sought to fulfil a prophecy delivered to him in early youth by a Gaulish Druidess, that he should mount a throne as soon as he had slain the wild-boar (Aper). These events took place in the course of the year 284, known in chronology as the era of Diocletian, or the era of the martyrs, an epoch long employed in the calculations of eccle- siastical writers, and still in use among Coptic Christians. After the ceremonies of installation had been completed at Nicomedeia, it became neces- sary to take the field forthwith against Carinus, who was hastening towards Asia at the head of a numerous and well-disciplined army. The oppos- ing armies met near Margus in upper Moesia, and, after an obstinate straggle, victory declared for the hardy veterans of the Western legions ; but while Carinus was hotly pursuing the flying foe he was slain by his own officers [Carinus]. His troops, left without a leader, fraternized with their late enemies, Diocletian was acknowledged by the conjoined armies, and no one appeared prepared to dispute his claims. The conqueror used his victory with praiseworthy and politic moderation. There were no proscriptions, no confiscations, no banish* 3x2
