Any representation of the human form has traditionally been discouraged in Islamic art, helping Arabic calligraphy to thrive in its place.

BBC: The Koran through the ages

Because the best abstract art has the power to cut through the rigid conventions of direct representation and externalize interior essences to show us things not as they look, but as they are.

WSJ: The Seductive Lure of Abstraction | Sightings by Terry Teachout