○/enso — An Ensō Drawn by Your Brainwaves

Can you draw a perfect circle?

The circle is one of the most beautiful forms in mathematics — yet none exist in reality. In Zen, a single brushstroke circle called ensō is said to reveal the mind of the one who draws it. This work reads your brainwaves and draws a circle based on your concentration. The deeper you focus, the closer the circle approaches perfection.

Circles and infinity do not exist in reality

The perfect circle described by the equation x² + y² = r² exists only as an ideal. However precise the machine, magnify any drawn circle and you will find distortion. In this work, whether the circle approaches perfection is left to the state of mind of the one who draws it. Circles and infinity do not exist in reality. They appear only when you concentrate.

How it works

An EEG headband (Muse 2) measures your brainwaves and computes a concentration score (0–100%)
After a calibration of 15 seconds of relaxation and 15 seconds of focus, a 60-second drawing begins
The angle advances 6° every second, completing exactly one revolution in 60 seconds. The radius is r(θ) = 80 + 20 × concentration(θ) [mm]
The higher your concentration, the deeper the brush presses, making the line thicker and bolder
If your concentration stays constant, r stays constant — a perfect circle. Every fluctuation of the mind remains on paper as a distortion of the circle
The one-of-a-kind circle, drawn by a pen plotter (AxiDraw) with a brush pen on half-size hansetsu washi paper, can be taken home by the participant