I took fewer pictures than I might have done on Wednesday if I hadn't got intrigued by geometric art, much of it, as with other features of the mosque, based on 4. Sometimes this was 'simple' as with the third and fourth images with two squares, one inverted to form a star. The door decoration was more complex with an 8-star in the first and a 12-star in the second, each multiples of 4. These complex geometric designs create the impression of unending repetition, demonstrating that, in the small, you can find the infinite, reminding Muslims that Allah is infinite. Circles have no end and so are also present. Calligraphy is a major art form in Islam and the Mosque walls in many places, including the exterior, are decorated with calligraphy portrayed with bricks.
This ancient use of geometry and repeating patterns as the language of the universe is reflected in scientific studies on the crystalline structure of matter.