Islamic Caligraphy

Introduction
While many religions have made use of figural images to convey their core convictions, Islam has instead used the shapes and sizes of words or letters. Because Islamic leaders saw in figural arts a possible implication of idolatry, Islam's early theocracy looked to the artistry of calligraphy for religious expression. In Islamic and Arabic cultures, calligraphy became highly respected as an art -- the art of writing.
Scholar Yasin Hamid Safadi (1978) writes:

The primacy of the word in Islam is reflected in the virtually universal application of calligraphy. Writing is given pride of place on all kinds of objects--objects of everyday use as well as entire wall surfaces, mosque furniture, the interiors and exteriors of mosques, tombs, and al-Ka'ba, the most famous sanctuary of Islam. But like the icons of most other faiths, script also represents power. Its preeminent use is the writing of the divine message of the Qur'an, of course, which endowed it with extraordinary strength and transcendent significance. From this world's manifold possibilities, Allah had chosen Arabic as the vehicle for his final revelation.

Arabic calligraphy is a primary form of art for Islamic visual expression and creativity. Throughout the vast geography of the Islamic world, Arabic calligraphy is a symbol representing unity, beauty, and power. The aesthetic principles of Arabic calligraphy are a reflection of the cultural values of the Muslim world. A thorough investigation into the aesthetic differences between Arabic and non-Arabic calligraphy might provide an approach for understanding the essential spirit of each culture.

http://www.islamicart.com/main/calligraphy/