The Holy Scripture of Islam. Muslims believe the Koran to be the word and will of God, as revealed to his messenger Muhammad (570–632) through the angel Jibril or Gabriel over the period (610–32). Written in classical Arabic, it consists of 114 sūras (chapters) of varying length, each sūra being composed of a number of āyas (normally translated as verses because assonance is involved, although the Koran is a prose work). The first revelation on Lailat al-Qadr, the Night of Power, is commemorated during the month of Ramadan. The early revelations are highly charged and rhetorical, but the style becomes more relaxed with the passing of time. The contents are diverse, particularly prominent themes being the omnipotence of Allah, the duty to believe in Allah alone, descriptions of the Day of Judgement, heaven, and hell, stories of the Prophets, and, in the latest phase, social legislation. Since the Koran is regarded by Muslims as a literal transcription of God’s revelations, for many years translations of the text were not permitted, and although today translations do exist, Muslims are taught to memorize and chant the original Arabic text. Calligraphic renditions of the text are a distinctive aid to worship in Islam.