Classical Arabic is the language of the Qur’an, the sacred text of Islam. Although people of many languages and cultures follow the Islamic faith, the Qur’an is always written in Arabic, the language in which the Qur’an was originally revealed to the Prophet Muhammad. With the spread of Islam that began in the 7th century CE, Arabic became the language of religion, government, commerce, literature, and science from the Arabian peninsula to the southern and eastern shores of the Mediterranean and through Iraq and Iran to Central Asia. The Arabic language, expressed in Arabic script, fostered cultural coherence across southern Europe and Asia and was also an outlet for artistic expression. Copies of the Qur’an are not accompanied by pictures, because pictorial illustration is considered a sacrilegious appropriation of God's prerogative of creation, but stylistic modulation and ornamentation of Arabic script were accepted and encouraged. Consequently, Arabic calligraphy became the most important aesthetic expression of Islamic civilization.