The Enso (Japanese for 'circle') is a Zen symbol of the absolute, the true nature of existence and enlightenment. It is a symbol that combines the visible and the hidden, the simple and the profound, the empty and the full. As an expression of infinity, it has links to the western lemniscate, and may be painted so that there is a slight opening somewhere in the circle, showing that the Enso is not contained in itself, but that it opens out to infinity. The enso, a simple circle drawn with a single, broad brushstroke, is the zen symbol of infinity. It represents the infinite void, the 'no-thing,' the perfect meditative state, and Satori (enlightenment.)

The Zen symbol "supreme" is an enso, a circle of enlightenment. The Shinjinmei, written in the sixth century, refers to the Great Way of Zen as "A circle like vast space, lacking nothing, and nothing in excess," and this statement is often used as an inscription on enso paintings. The earliest reference to a written enso, the first Zen painting, occurs in the Keitokudento-roku, composed in the eighth century: A monk asked Master Isan for a gatha expressing enlightenment. Isan refused saying, "It is right in front of your face, why should I express it in brush and ink?" The monk then asked Kyozan, another master, for something concrete. Kyozan drew a circle on a piece of paper, and said, "Thinking about this is and then understanding it is second best; not thinking about it and understanding it is third best." (He did not say what is first best.) Thereafter Zen circles became a central theme of Zen art. Enso range in shape from perfectly symmetrical to completely lopsided and in brushstroke (sometimes two brushstrokes) from thin and delicate to thick and massive. Most paintings have an accompanying inscription that gives the viewer a "hint" regarding the ultimate meaning of a particular Zen circle. The primary types of enso are: (1) Mirror enso: a simple circle, free of an accompanying inscription, leaving everything to the insight of the viewer. (2) Universe enso: a circle that represents the cosmos (modern physics also postulates curved space). (3) Moon enso: the full moon, clear and bright, silently illuminating all beings without discrimination, symbolizes Buddhist enlightenment. (4) Zero enso: in addition to being curved, time and space are "empty," yet they give birth to the fullness of existence. (5) Wheel enso: everything is subject to change, all life revolves in circles. (6)Sweet cake enso: Zen circles are profound but they are not abstract, and when enlightenment and the acts of daily life-"sipping tea and eating rice cakes"-are one, there is true Buddhism. (7) "What is this?" enso: the most frequently used inscription on Zen circle paintings, this is a pithy way of saying, "Don't let others fill your head with theories about Zen; discover the meaning for yourself!"

Yin and Yang

One yin, one yang, that is the Tao.
Chapter 5, Hsi-tz'u of the I Ching

The quotation above is the first known reference to yin and yang, the pair of polar energies whose cyclic fluctuations and interactions cause and govern Creation. Together they are polar expressions of the supreme ultimate, t'ai-chi, the eternal Tao. Yin originally was the name given to the colder, north-facing slope of a mountain, and yang to the warmer, southern, sun-facing one. Thus yin corresponds to the dark, the receptive, the passive, the feminine; while yang corresponds to the bright, the creative, the active, the masculine. Yin is the moon, water and the earth. Yang is the sun, fire and the heavens.

One symbolic system of representing the mutual fluctuations of these energies is the trigrams of the I Ching, another is the famous symbol shown above. It is a dynamic symbol, showing the continual interaction and balance of the two energies, and as such it is a very harmonizing symbol. As each of the energies reaches its apogee, it begins to transform into its opposite, and this is shown by the dots in the symbol. At its height yang contains the seed of yin, just as yin contains the seed of yang.

Lao-tzu in the Tao-te ching wrote: 'Everything has both yin and yang in it -- and from their rise-and-fall coupling comes new life.'

	Yin	Yang
Nature	feminine	masculine
	passive	active
	receives	creates
	soft	hard
	dark	bright
Symbols	moon	sun
	tiger	dragon
	north	south
Colour	black	red
Numbers	even	odd
Chinese character
Original meaning	north side of a hill (i.e. away from the sun)	south side of a hill (i.e. facing the sun)