OMAR (c. 581-644)  , in full 'OMAR IBN AL-KHATTAB, the second of the Mahommedan caliphs (see CALIPHATE, A, §§ 1 and 2) . Originally opposed to Mahomet, he became later one of the ablest advisers both of him and of the first caliph, Abu Bekr . His own reign (634–644) saw Islam's transformation from a religious sect to an imperial power . The chief events were the defeat of the Persians at Kadisiya (637) and the conquest of Syria and Palestine . The conquest of Egypt followed (see EGYPT and AMR IBN EL-Ass) and the final rout of the Persians at Nehawend 041) brought Iran under Arab rule . Omar was assassinated by a Persian slave in 644, and though he lingered several days after the attack, he appointed no successor, but only a body of six Muhajirun who should select a new caliph . Omar was a wise and far-sighted ruler and rendered great service to Islam . He is said to have built the so-called " Mosque of . Omar " (" the Dome of the Rock ") in Jerusalem, which contains the rock regarded by Mahommedans as the scene of Mahomet's ascent to heaven, and by the Jews as that of the proposed sacrifice of Isaac . 'OMAR KHAYYAM [in full, GHIYATHUDDIN ABULFATH 'OMAR BIN IBRAHIM AL-KHAYYAMI], the great Persian mathematician, astronomer, freethinker and epigrammatist, who derived the epithet Khayyam (the tentmaker) most likely from his father's trade, was born in or near Nishapur, where he is said to have died in A.H . 517 (A.D . 1123) .

At an

early age he entered into a close friendship both with Nizam-ul-mulk and his school-fellow IJassan ibn Sabbath, who founded afterwards the terrible sect of the Assassins . When Nizam-ul-mulk was raised to the rank of vizier by the Seljuk sultan Alp-Arslan (A.D . 1063–1073) he bestowed upon IJassan ibn Sabbab the dignity of a chamber-lain, whilst offering a similar court office to 'Omar Khayyam . But the latter contented himself with an annual stipend which would enable him to devote all his time to his favourite studies of mathematics and astronomy . His standard work on algebra, written in Arabic, and other treatises of a similar character raised him at once to the foremost rank among the mathematicians of that age, and induced Sultan Malik-Shah to summon him in A.H . 467 (A.D . 1074) to institute astronomical observations on a larger scale, and to aid him in his great enterprise of a thorough reform of the calendar . The results of 'Omar's research were—a revised edition of the Zij or astronomical tables, and the introduction of the Ta'rikh-i-Malikshahi or Jalali, that is, the so-called Jalalian or Seljuk era, which commences in A.H . 471 (A.D . 1079, 15th March) . 'Omar's great scientific fame, however, is nearly eclipsed by his still greater poetical renown, which he owes to his rubd'is or quatrains, a collection of about 500 epigrams . The peculiar form of the rubd'i—viz. four lines, the first, second and fourth of which have the same rhyme, while the third usually (but not always) remains rhymeless—was first successfully introduced into Persian literature as the exclusive vehicle for subtle thoughts on the various topics of Sufic mysticism by the sheikh Abu Said bin Abulkhair,' but 'Omar differs in its treatment considerably from Abu Said .

Although some of his quatrains are purely mystic and pantheistic, most of them

bear quite another stamp; they are the breviary of a radical freethinker, who protests in the most forcible manner both against the narrowness, bigotry and uncompromising austerity of the orthodox ulema and the eccentricity, hypocrisy and wild ravings of advanced Sufis, whom he successfully combats with their own weapons, using the whole mystic terminology simply to ridicule mysticism itself . There is in this respect a great resemblance between him and Hafiz, but 'Omar is decidedly superior . He has often been called the Voltaire of the East, and cried down as materialist and atheist . As far as purity of diction, fine wit, crushing satire against a debased and ignorant clergy, and a general sympathy with suffering humanity are concerned, 'Omar certainly reminds us of the great Frenchman; but there the comparison ceases . Voltaire never wrote anything equal to 'Omar's fascinating rhapsodies in praise of wine, love and all earthly joys, and his passionate denunciations of a malevolent and inexorable ' Died Jan . 1049 . Comp . Eth6's edition of his ruba'is in Sitzungsberichte der bayr . Akademie (1875), pp . 145 seq., and (1878) pp . 38 seq . ; and E .

G .

Browne's Literary Hist, of Persia, ii . 261 . fate which dooms to slow decay or sudden death and to eternal oblivion all that is great, good and beautiful in this world . There is a touch of Byron, Swinburne and even of Schopenhauer in many of his ruba'is, which clearly proves that the modern pessimist is by no means a novel creature in the realm of philosophic thought and poetical imagination . The Leiden copy of 'Omar Khayyam's work on algebra was noticed as far back as 1742 by Gerald Meerman in the preface to his Specimen calculi fluxionalis; further notices of the same work by Sedillot appeared in the Nouv . Jour . As . (1834) and in vol. xiii. of the Notices et extraits des MSS. de la Bibl. ray . The complete text, together with a French translation (on the basis of the Leiden and Paris copies, the latter first discovered by M . Libri, see his Histoire des sciences mathematiques en Italic, i . 300), was edited by F .

Woepcke, L'Algebre d'Omar Alkhayyami (Paris, 1851) . Articles on 'Omar's

life and works are found in Reinaud's Geographie d'Aboulfeda, pref., p . 1o1; Notices et extraits, ix . 143 seq.; Garcia de Tassy, Note sur les Ruba'iyat de 'Omar Hhaiyam (Paris, 1857) ; Rieu, Cat . Pers . MSS. in the Br . Mus., ii . 546; A . Christensen, Recherches sur les Ruba'iyat de 'Omar Hayyam (Heidelberg, 1905) ; V . Zhukovski's ' Umar Khayyam and the " Wandering " Quatrains, translated from the Russian by E . D . Ross in the Journal of the Royal Asiatic Society, xxx .

(1898); E . G . Browne, Literary

History oPersia, ii . 246 . The quatrains have been edited at Calcutta (1836) and Teheran (1857 and 1862); text and French translation by J . B . Nicolas (Paris, 1867) (very incorrect and misleading) ; a portion of the same, rendered in English verse, by E . FitzGerald (London, 1859, 1872 and 1879) . FitzGerald's translation has been edited with commentary by H . M . Batson (1900), and the and ed. of the same (1868) by E . Heron Allen (1908) .

A new English version was published in Triibner's "

Oriental " series (1882) by E . H . Whinfield, and the first critical edition of the text, with translation, by the same (1883) . Important later works are N . H . Dole's variorum edition (1896), J . Payne's translation (1898), E . Heron Allen's edition (1898) and the Life by J . K . M . Shirazi (1905); but the literature in new translations and imitations has recently multiplied exceedingly . (H .