Inspired by Japanese Ensos, the word for "circular form". They are also known as Zen circles and a symbol for enlightenment.
Sometimes they darker, sometimes they are lighter. Sometimes they are closed, sometimes they are not. But they are never perfect. Every now and then the attempt to draw a circle even fails completely.

The path of the strokes follows a set of trigonometric metric functions with small random disturbances to mimic brush strokes of a calligraphist.