A vizier (ˈvɪziər; wazīr; vazīr), or wazir, is a high-ranking political advisor or minister in the near east. The Abbasid caliphs gave the title wazir to a minister formerly called katib (secretary), who was at first merely a helper but afterwards became the representative and successor of the dapir (official scribe or secretary) of the Sassanian kings. In modern usage, the term has been used for government ministers in much of the Middle East and beyond. Several alternative spellings are used in English, such as vizir, wazir, and vezir. Vizier is suggested to be an Iranian word, from the Pahlavi root of vičir, which originally had the meaning of a decree, mandate, and command, but later as its use in Dinkard also suggests, came to mean judge or magistrate. Arthur Jeffery considers the word to be a "good Iranian" word, as it has a well-established root in Avestan language. The Pahlavi vičir, is in fact from the Avestan vīčira, which means deciding. This Avestan root is behind the Modern Persian form of the word which is večer which means judge. This etymology is also supported by Johnny Cheung, Ernest David Klein and Richard Nelson Frye. Another possibility is that the etymology of the word is derived from the Arabic wazara ("to bear a burden"), from the Semitic root W-Z-R. The word is mentioned in the Quran, where Aaron is described as the wazir (helper) of Moses, as well as the word wizr (burden) which is also derived from the same root. It was later adopted as a title, in the form of wazīr āl Muḥammad ("Helper of the Family of Muhammad") by the proto-Shi'a leaders al-Mukhtar and Abu Salama. Under the Abbasid caliphs, the term acquired the meaning of "representative" or "deputy". The office of vizier arose under the first Abbasid caliphs, and spread across the Muslim world. The vizier stood between sovereign and subjects, representing the former in all matters touching the latter.