While the exact date and location of the origin of Arabic writing is debated, the earliest evidence dates to the 6th century AD. The prophet Muhummad's revelations, which were recorded as the contents of the Qu'ran, occurred in the early part of the 7th century. During the spread of Islam in subsequent centuries, a legible script printed on parchment was essential for transporting and sharing the Qu'ran. In the 9th century, paper became the preferred medium, which led to the development of a more fluid, cursive script in place of the more angular style of the past; paper permitted not only the spread of religious texts, but also the publishing of large numbers of secular books. Farsi calligraphy reached its height around 1400 AD and was regularly used for poetry. While Arabic continued to be the language of sacred texts, Farsi was considered the language of highest literary merit, even as far away as the Ottoman and Mughal empires (present-day Turkey and India, respectively). Images of God were forbidden by the Qu'ran, and figurative art was often suspected of idolatry, so calligraphy is amongst the highest art forms in the Muslim world. Contemporary uses of calligraphy can be found in Ghada Amer's sculptures, Shirin Neshat's photography, and Shahzia Sikhander's drawings and paintings.