A Dictionary of Greek and Roman biography and mythology. By various writers. Ed. by William Smith. Illustrated by numerous engravings on wood.

DIOCLES.
date, who wrote repI srvpiwv, according to Eutocius
who has cited from that book (Conmm. in Sph. et
Cycl. Archim. lib. ii. prop. v.) his method of dividing a sphere by a plane in a given ratio. But
he is better known by another extract which Eutocius (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 cissoid, and is too well known
to geometers to need description. [A. DE M.]
DFOCLES CARYSTIUS (AoicAX d' Kapv`-ios), a very celebrated Greek physician, was born
at Carystus in Euboea, and lived in the fourth
century a. c., not long after the time of Hippocrates,
to whom Pliny says he was next in age.and fame.
(I. N. xxvi. 6.) He 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 'E7rtoroA7i
TIpopvAaKTruc4, "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, was 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, Aneed. Med. Graeea, praef. p.
xiv.), and treats of the diet fitted for the different 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, Biblioth. Graeca; and in
Mich. Neander's Syllogce Physicae, Lips. 1591,
8vo.; and in Latin with Alexander Trallianus, Basil. 1541, fol.; and Meletius, Venet. 1552, 4to. &c.
There is also a German translation by Hieronymus
Bock, in J. Dryander's Practicirbhchlein, Frankfort, 1551, 8vo. 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 connected with his name. Further information respecting him may be found in the different histories
of medicine, and also in Fabricius, Biblioth. Graeca,
vol. xii. p. 584, ed. vet.; A. Rivinus, Programma
de Diode Carystio, Lips. 1655, 4to.; C. G. Gruner,
Bibliothek der Alten Aerzte, Leipz. 1781, 8vo. vol.
ii. p. 605; C. G. KUihn, Opuscula Academ. Med. et
Philolog. Lips. 1827, 8vo. 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 Obstetr. pp. 15, 16, 67, 99,
124, 210, 257, 265; and in Cramer's Anecd. Graeca
Paris. vol. i. p. 394, and vol. iv. p. 196. [W. A. G.]
DI'OCLES, JULIUS ('lovAmos AtocAXs), of
Carystus, the author of four epigrams in the Greek
Anthology. (Brunck, Anal. ii. 182; Jacobs, ii.
167.) His name implies that he was a Greek,
and had obtained the Roman civitas. Reiske supposed him to be the same person as the rhetorician
Diodes of Carystus, who is often mentioned by
Seneca. 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. S.]

DIOCLETIANUS. 1011
DIOCLETIA'NUS VALE'RIUS, was born
near Salona in Dalmatia, in the year A. D. 245, of
most obscure parentage; his father, according to
the accounts commonly received, which are, however, 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 he must
have been born 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 appellation of Docles or Diodes, which, after his assumption 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 various subordinate grades, was appointed to most important commands under Probus and Aurelian, in
process of time was elevated to the rank of consul
suffectus, followed Carus to the Persian war, and,
after the death of that emperor on the banks of the
Tigris [CARus], remained attached to the court during the retreat in the honourable capacity of chief
captain of the palace guards (domestici). 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 accepted the proferred dignity, signalized his accession 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 disinterested zeal, was less eager to satisfy the demands
of justice than to avert suspicion from himself and
to remove a formidable rival, especially since he
did not scruple to confess that he had long anxiously 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 ecclesiastical writers, and still in use among Coptic
Christians. After the ceremonies of installation
had been completed at Nicomedeia, it became necessary to take the field forthwith against Carinus,
who was hastening towards Asia at the head of a
numerous and well-disciplined army. The opposing armies met near Margus in upper Moesia, and,
after an obstinate struggle, 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.
3T 2