CÆSAR. The Arabic and Persian form of the Latin Cæsar is Qaisar. The word occurs in the traditions of the Sahihu ‘l-Mus1im (vol. ii p.99), where it is applied to the Emperor Heraclius who received a letter from Muhammad inviting him to Islam, when he was at Edessa on his way to Jerusalem, August, A.D. 628. The origin of the title is uncertain. Spartianus, in his life of Aelius verus (c. ii) mentions four different opinions respecting its origin: (1) That the word signified an elephant in the language of the Moors, and was given as a surname to one of the Julii because he had killed an elephant; or (2) That it was given to one of the Julii because he had been cut (caesus out of his mother’s womb after her death; or (3) Because he had been born with a great quantity of hair (caesaries) on his head; or (4) Because he had azure-coloured (caesii) eyes. Of these opinions the second is the one adopted by the Arabic-Persian Dictionary the Ghiyan ‘l-Lughat.
The first of the Julian family who occurs in history as having obtained the surname of Cæsar is Sex. Julius Cæsar, prætor in B.C. 208. It was first assumed as an imperial title by Augustus as the adopted son of the dictator, and was by Augustus handed down to his adopted son Tiberius. It continued to be used by Caligula, Claudius, and Nero, as members, either by adoption or female descent of Cæsar’s family; but though the family became extinct with Nero, succeeding emperors still retained it as part of their titles, and it was the practice to prefix it to their own name, as for instance, Imperator Cæsar Domitianus Augustus. The title was superseded in the Greek Empire under Alexis Commenus by that of Sebastocrator. In the west, it was conferred on Charles the Great, and was borne by those who succeeded him on the imperial throne. Although this dignity came to an end with the resignation Francis II, in 1806, the title Kaiser is still assumed by the Emperors of Austria and Germany, and more recently by the Queen of England as Qaisar-i-Hind or Empress of India.
Based on Hughes, Dictionary of Islam