Zen Symbol

If Zen had a symbol, it might be the following:

A circle -- known as "enso" in Japanese -- universally implies completeness, all.

A zen circle can also imply zero, sunyata, absolute, true reality, enlightenment, no beginning/no end in all phenomena, no symbol, the spread of Dharma as a turning wheel, harmony, and womb.

Calligraphy by Kazuaki Tanahashi.

From: The Complete Idiot's Guide to Understanding Buddhism, by Gary Gach.