Arabic calligraphy was destined to become a major art, indeed, the principal art for centuries. Not until the fifteenth and sixteenth centuries did painting catch up with it...Its own inherent plastic qualities are conducive to setting up rhythms through repetitions... If proof is needed that Arabian calligraphy possesses aesthetic qualities independent of meanings expressed, there is the fact that it was used purely as decoration in Byzantine works, in early Italian paintings, and even on the facades of medieval French churches,  as at Le Puy; the characters are generally only pseudo-Arabic, which is good evidence that the artists who devised these inscriptions were responsive to the beauty of the pure forms of Arabian calligraphy​.
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A. Papadopoulo, Islam and Muslim Art (1979)