or evil spirit in Arabic mythology, associated with graveyards and consuming human flesh, demonic being believed to inhabit burial grounds and other deserted places. In ancient Arabic folklore, ghūls belonged to a diabolic class of jinn (spirits) and were said to be the offspring of Iblīs, the prince of darkness in Islam. They were capable of constantly changing form, but their presence was always recognizable by their unalterable sign—ass's hooves. which describes the ghūl of Arabic folklore. The ghul is a devilish type of jinn believed to be sired by Iblis. Literature The Quran, the main holy book of Islam, had a significant influence on the Arabic language, and marked the beginning of Islamic literature. Muslims believe it was transcribed in the Arabic dialect of the Quraysh, the tribe of Muhammad. As Islam spread, the Quran had the effect of unifying and standardizing Arabic. Not only is the Quran the first work of any significant length written in the language, but it also has a far more complicated structure than the earlier literary works with its 114 suwar (chapters) which contain 6,236 ayat (verses). It contains injunctions, narratives, homilies, parables, direct addresses from God, instructions and even comments on how the Quran will be received and understood. It is also admired for its layers of metaphor as well as its clarity, a feature which is mentioned in An-Nahl, the 16th surah. Al-Jahiz (born 776, in Basra – December 868/January 869) was an Arab prose writer and author of works of literature, Mu'tazili theology, and politico-religious polemics. A leading scholar in the Abbasid Caliphate, his canon includes two hundred books on various subjects, including Arabic grammar, zoology, poetry, lexicography, and rhetoric. Of his writings, only thirty books survive. Al-Jāḥiẓ was also one of the first Arabian writers to suggest a complete overhaul of the language's grammatical system, though this would not be undertaken until his fellow linguist Ibn Maḍāʾ took up the matter two hundred years later. There is a small remnant of pre-Islamic poetry, but Arabic literature predominantly emerges in the Middle Ages, during the Golden Age of Islam. Literary Arabic is derived from Classical Arabic, based on the language of the Quran as it was analyzed by Arabic grammarians beginning in the 8th century. A large portion of Arabic literature before the 20th century is in the form of poetry, and even prose from this period is either filled