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Diocletian ► Dior I 549
Diocletian y.dl-s-'kle-shonX Latin Gaius Aurelius Valerius Dio- cletianus orig. Diodes (b. ad
245, Salonae?, Dalmatia—d. 316,
Salonae) Roman emperor (284- 305). He was serving under the emperor Carinus (r. 283-285) when the co-emperor, Carinus’s brother Numerian, was killed. Diocletian’s army declared him emperor, but his domain was restricted to Asia Minor and possibly Syria. Carinus attacked Diocletian (285) but was assassi¬ nated before achieving victory, allowing Diocletian to become sole emperor. He sought to remove the military from politics and estab¬ lished a tetrarchy (four-ruler system) to spread his influence and combat rebellions throughout the empire.
Proclaiming himself and his corulers as gods, he added the trappings of a theocracy to the reign. His fiscal, administrative, and military reorga¬ nization laid the foundation for the Byzantine empire in the east and briefly strengthened the fading empire in the west. In 303-304 he issued four edicts decreeing the last great per¬ secution of Christians. He abdicated in 305.
Diocletian window Semicircular window divided into three lights (compartments) by two vertical mullions, with the central light usually wider than the two side lights. Its name comes from its use in the Baths of Diocletian in Rome (ad 302). It was revived in the 16th century by Andrea Palladio and others in the form of a window having an arched cen¬ tral light flanked by narrower, square-headed apertures, known as a Pal- ladian or Venetian window.
diode Electronic device that has two electrodes (anode and cathode) and that allows current to flow in only one direction, resisting current flow in the other. An applied voltage can cause electrons to flow in only one direction, from the cathode to the anode, and then back to the cathode through an external circuit. Diodes are used especially as rectifiers— which change alternating current into direct current —and to vary the amplitude of a signal in proportion to the voltage in a circuit, as in a radio or television receiver. The most familiar diodes are vacuum tubes and semi¬ conductor diodes. Semiconductor diodes, the simplest of semiconductor devices, consist of two electrodes and a sandwich of two dissimilar semi¬ conducting substances (a p-n junction). Such diodes form the basis for more complex semiconductor devices (including transistors) used in com¬ puters and other electronic equipment. Semiconductor diodes include light-emitting diodes and laser diodes; the latter emit laser light, useful for telecommunications via fibre optics and for reading compact discs.
Diogenes of Sinope \dI-'aj-3- l nez...s3- , n6-pe\ (b. Sinope,
Paphlygonia—d. c. 320 bc, probably Corinth) Greek philosopher, princi¬ pal member of the Cynics. He is credited by some with originating the Cynic way of life, but he himself acknowledged his debt to Antisthenes (c. 445-365 bc). He conveyed the Cynic philosophy by personal example rather than through any system of thought. He strove to destroy social conventions (including family life) as a way of returning to a “natural” life. To this end he lived as a vagabond pauper, sleeping in public build¬ ings and begging for food. He also advocated shamelessness (performing harmless unconventional actions), outspokenness, and training in auster¬ ity.
Diomede VdI-3-,med\ Islands Two islands in the Bering Strait. Lying about 2.5 mi (4 km) apart, they are separated by the U.S.-Russian bound¬ ary, which coincides with the International Date Line. The larger island, Big Diomede (Russian Ratmonov), belongs to Russia and is the site of an important weather station. To the east lies Little Diomede Island, a part of Alaska.
Diomedes \ 1 dI-3-'me- l dez\ Greek hero in the Trojan War. He was com¬ mander of 80 ships from Argos bringing soldiers to defeat Troy. His exploits included wounding the goddess Aphrodite, killing Rhesus and his Thracian followers, and stealing the Trojan Palladium (the sacred image of Athena that protected Troy). Aphrodite punished him by making his
wife unfaithful to him in his absence, and after the war he returned home to find his claim to the throne of Argos disputed. He then sailed to Italy and founded the colony of Argyripa (later Arpi) in Apulia.
Dionysia See Bacchanalia
Dionysius I or Dionysius the Elder (b. c. 430 bc —d. 367) Tyrant of Syracuse (405-367). He became ruler with Spartan help and retained power until his death, basing his strength on the support of his mercenary army. He held Carthaginian expansion on Sicily in check and hoped to acquire an empire in Greek Italy. Syracuse’s economy depended on war, and under Dionysius great advances were made in the technology of large-scale artillery and the manufacture of munitions. His disastrous third campaign against the Carthaginians resulted in the ceding of money and territory; he died during the next Carthaginian conflict.
Dionysius of Halicarnassus (fl. c. 20 bc) Greek historian and teacher of rhetoric. Born in Halicarnassus, Caria (Asia Minor), Dionysius went to Rome in 30 bc. His history of Rome, from its origins to the First Punic War, is written from a pro-Roman standpoint but carefully researched. It is, with Livy’s, the most valuable source for early Roman history. Its 20 books began to appear in 7 bc; the last 10 have been lost.
Dionysius the Areopagite X.ar-e-'a-po-jlt, .ar-e-'a-ps-.gfiA (fl. 1st century) Biblical figure, converted by St. Paul. His conversion at Athens is mentioned in Acts 17:34, and he acquired a posthumous reputation largely through confusion with later Christians similarly named. Around ad 500, a series of influential Greek treatises uniting Neoplatonism and Christian theology were forged in his name; the writer, probably a Syr¬ ian monk, is now known as Pseudo-Dionysius the Areopagite.
Dionysus \,dI-9-'nI-s9s\ Greek god of vegetation and fruitfulness, known especially as the god of wine and ecstasy. His Roman equivalent was Bacchus. His worship was introduced into Greece from Asia Minor, and he became one of the most important of all the Greek gods, while his cult remained associated with that of many Asiatic deities. A son of Zeus and (according to the standard tradition) Semele, he was brought up by the maenads, or bacchantes. The first creator of wine, he traveled widely teach¬ ing the winemaking art, with a following of satyrs, sileni (see satyr and silenus), and nymphs. He had the gift of prophecy and was received at Del¬ phi along with Apollo, though his principal oracle was at Thrace. Festivi¬ ties called Dionysia or (among the Romans) Bacchanalia were held in his honor; in their earlier years they were wild, ecstatic occasions, and they have often been the subject of artistic representation. Dionysus originally appeared as a bearded man, but later more often as a slim youth. His prin¬ cipal attribute was the thyrsus, a wand bound with vine leaves. The dithyramb, a choral hymn in his honor, is often seen as the basis of West¬ ern drama.
Diop VjopV Birago Ismael (b. Dec. 11, 1906, Dakar, French West Africa—d. Nov. 25, 1989, Dakar) Senegalese poet and recorder of tradi¬ tional Wolof folktales. A veterinarian and diplomat, he was active in the Negritude movement in the 1930s. His output of lyric poetry is small but the poetry is beautifully composed. His books containing tales told to him by his family’s griot include Tales of Amadou Koumba (1947) and Tales and Commentaries (1963).
diopside \dl-'ap-,sld\ Common silicate mineral in the pyroxene family. Diopside is a calcium and magne¬ sium silicate (CaMgSi 2 0 6 ) that occurs in metamorphosed siliceous limestones and dolomites, in skarns, and in igneous rocks. It is also found in small amounts in many chondritic meteorites. Clear specimens of good green colour are sometimes cut as gems.
Dior \'dy6r,\ English \de-'or,
'de-orV Christian (b. Jan. 21,
1905, Granville, France—d. Oct. 24,
1957, Montecatini, Italy) French fashion designer. He trained for the French diplomatic service, but in the financial crisis of the 1930s he began illustrating fashions for a weekly periodical. In 1942 he joined the Christian Dior, 1957. house of the Parisian designer encyclopedia britannica, inc.