It's hard to overstate the incredible clarity and beauty of traditional Arabic calligraphy. Calligraphy was and is a major element of Islamic design, found on household objects, weapons and armor, and embedded in architecture. Calligraphy, like Egyptian heiroglyphics, was used as both art and communication.
This bowl is from the Samanid dynasty of Medieval Persia, when Islamic culture was being enriched by Persia's (now Iran's) many artists, poets and craftsmen. This bowl carries the message:
التدبیر قبل العمل یؤمنك من الندم الیمن والسلامه
Planning before work protects you from regret; good luck and well-being