CAIUS VALERIUS JOVIVS, a celebrated Roman emperor, born of an obscure family in Dalmatia in 245. He was first a common soldier, and by merit and success he gradually rose to the office of a general; and at the death of Numerian in 284, he was invested with imperial power. In this high station he rewarded the virtues and fidelity of Maximian, who had shared with him all the subordinate offices in the army, by making him his colleague on the throne. He created two subordinate emperors, Constantius and Galerius, whom he called Caesars, whilst he claimed for himself and his colleague the superior title of Augustus. Dioclesian has been celebrated for his military virtues; and though he was naturally unpolished by education and study, yet he was the friend and patron of learning and true genius. He was bold and resolute, active and diligent, and well acquainted with the arts, which will endear a sovereign to his people, and make him respectable even in the eyes of his enemies. His cruelty, however, against the followers of Christianity, has been deservedly branded with infamy. After he had reigned 22 years in the greatest prosperity, he publicly ab- Dioclesian dicated the crown at Nicomedia in 305, and retired to a private station at Salona. Maximian his colleague followed his example, but not from voluntary choice; and when he some time after endeavoured to rouse the ambition of Dioclesian, and persuade him to reassume the imperial purple, he received for answer, that Dioclesian took now more delight in cultivating his little garden than he formerly enjoyed in a palace, when his power was extended over all the earth. He lived nine years after his abdication in the greatest security and enjoyment at Salona, and died in 314, in the 68th year of his age. Dioclesian is the first sovereign who voluntarily resigned his power. His bloody persecution of the Christians forms a chronological era, called the era of Dioclesian, or of the martyrs. It was for a long time in use in theological writings, and is still followed by the Copts and Abyssinians. It commenced August 29, 284.

Diodati, John, a famous minister, and professor of theology at Geneva, was born at Locca in 1579, and died at Geneva in 1652. He is distinguished by translations, 1. Of the Bible into Italian, with notes, Geneva, 1607, 4to. The best edition at Geneva in 1621, folio. This is said to be more a paraphrase than a translation, and the notes rather divine meditations than critical reflections. 2. Of the Bible into French, Geneva, 1644. 3. Of Father Paul's History of the Council of Trent into French.

Diodia, a genus of plants belonging to the te-trandria class, and in the natural method ranking under the 47th order, Stellate. See Botany Index.