Arabic Design is about harmony, unity, perpetuity. It is, as my late professor Dr. Gordon Bugbee would say, "A Unity that is Subdivided." Yet it is also about a certain innate, naturalist beauty that is ironically communicated through a delicate, measured geometric aesthetic.
Historically, it stems from the Islamic tradition of avoiding the depiction of human or animal figures in Muslim religious context (books, masjids, etc,) for religious reasons concerned with relinquishing idolatry. The artform thereby developed through the course of Muslim history from simple patterns to quite complex mathematical systems, giving birth to the pottery, architecture, page illustrations, textiles and sciences that infused people's lives, leading to the high Muslim Renaissance, and consequently influencing the visual arts of its neighboring cultures, from early Byzantium, to Persia, India and China in the east, to Florence and Spain in the west.
Below is a reconstitution of a series of posts over the last two weeks, in which I incrementally built one design in a series of daily steps.
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Four square quadrants constitute a major square; every quadrant subdivides into four sub-quadrants, a total of 16 subquadrants. One subquadrant from each quadrant is retained in the center of the major square; consequently four 1/16th squares come together in the center to become a square that is equal to any of the four quadrants of the original major square. Then four circles, each 5/6 of a 1/16th subquadrant. Why this dimension? just because.

So we have the four circles, they make a square,

We duplicate them, and rotate them 45°, all together as a square. Now we have eight;

On the other hand, let's first bring the four original circles closer together,
so that they touch adjacently at the center of the design,
and we can also show the square that is comprised of their four centers,

NOW we can rotate them 45°.

Result:

Let's add a circle, same size as the others, in the middle. It intersects perfectly and lovingly into the octagonal space that had been created by the two squares. We then place four more circles, adjacent to the center circle, to the north, south, east and west of the center circle.

We then rotate the entire group of four new circles at 45°, a rotation that will land them at the four corners of the center square:

So now we have eight circles rotated around the center,
plus another eight circles rotated around them,
plus a circle in the center,
as well as an eight-pointed star made up of two squares, rotated at 45°.

some more circles (the blue ones,)

and a few more circles (the black ones,)

and some new squares,

and we rotate each square (45°, of course.)

We have quite a complexity now, almost unbearable in its intricate detail, sort of like life some days, a precious stone in the rough, in need of shinning to bring out an understanding of its beauty, of why it is.

Now some attention to detail: A few additions, a few subtractions;
Like when spring comes back and the mud and snow melt away, and the mass disorder of your life begins to clear up, as in macro volumes of collected regret, so you start throwing away redundant clutter that you once thought was important, but then you find yourself reattaching yourself to newer detail, newer trinkets that you find at the hardware store, or the garden shop.

The structure is finalized.
Red is the color that binds the variant elements of a Unity that is Subdivided. Next more color.
. . . 
Red + Green =
+ 
=

The foliage-like shapes receive a color like the undersides of olive leaves.
. . . 
We increase the darkness of the outside & center green color, lighten the color of the leaf-shapes a bit, and deepen the red to be more like our blood.

We assign a deep, dark blue-green to a group of shapes, so we can have a restful place for our eyes sometimes; rest your eyes, rest your limbs, rest your breathing, and rest your mind.

And a bright-light yellow color for another group of shapes, so that we can satiate our desire for joy at other times.

A Bright orange to imply some circular groupings, and we're done!

How about a sense of infiniteness and perpetuity? o.k.:
We repeat the entire design in a couple of perfect spots, where it naturally fits.

Until it sings, like the boundless magnificence of the universe, and all of its peaceful, coexistent variety, the astounding creation that is nature, from the atoms to the galaxies, the wonder that comes forth from one origin. The center represents the Creator, One and Definite, yet Omnipresent within all of His creation, reappearing as signs of His own beauty.

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