Zen Buddhism
Zen is very simple... What are you?
In this whole world everyone searches for happiness outside, but nobody understands their true self inside.
Everybody says, "I" -- "I want this, I am like that..." But nobody understands this "I." Before you were born, where did your I come from? When you die, where will your I go? If you sincerely ask, "what am I?" sooner or later you will run into a wall where all thinking is cut off. We call this "don't know."
Zen is keeping this "don't know" mind always and everywhere.
When walking, standing, sitting,
lying down, speaking, being
silent, moving, being still.
At all times, in all places, without
interruption -- what is this?
One mind is infinite kalpas.
Meditation in Zen means keeping don't-know mind when bowing, chanting and sitting Zen. This is formal Zen practice. And when doing something, just do it. When driving, just drive; when eating, just eat; when working, just work.
Finally, your don't-know mind will become clear. Then you can see the sky, only blue. You can see the tree, only green. Your mind is like a clear mirror. Red comes, the mirror is red; white comes the mirror is white. A hungry person comes, you can give him food; a thirsty person comes, you can give her something to drink. There is no desire for myself, only for all beings. That mind is already enlightenment, what we call Great Love, Great Compassion, the Great Bodhisattva Way. It's very simple, not difficult!
So Buddha said that all beings have Buddha-nature (enlightenment nature). But Zen Master Joju said that a dog has no Buddha-nature. Which one is right? Which one is wrong? If you find that, you find the true way.
-- Zen Master Seung Sahn
And another version of Zen explanation
What is Zen?
The four lines below are traditionally attributed to Bodhidharma, 28th Indian Dharma Ancestor and First Ancestor of Zen in China:
A special transmission outside the scriptures,
Not relying on words and letters,
Pointing directly to the mind,
And personally realizing Buddhahood.
Whatever someone says about Zen is only a finger pointing at the moon. If our gaze fixes on the finger, we miss the moon. If we try to grasp intellectually the essential teaching of Zen, without engaging in actual practice, words and concepts will themselves block us from directly experiencing the wholeness and splendor of the Full Moon of our own heart-mind.
In traditional Japanese Zen temples, the only instruction a new applicant typically received was to 'go sit.' We Westerners, however, generally need something more to 'hook' our hungry intellects and get us motivated to start practicing.
On one hand, then, we can say that Zen is a school of Buddhism. While some schools emphasize the study of a particular sutra, or chanting, or devotional practices, Zen is the sect that most emphasizes the practice of silently and directly looking into the mind, and the transformative experience of waking up to the deepest truth of one's fundamental Buddha-nature.
When Buddhism migrated from India to China, it mixed with Taoism and Confucianism and gave birth to a new and vibrant practice known as Ch'an, the Chinese word for the Sanskrit dhyana, or meditation. Zen is the Japanese equivalent for Ch'an.
The foundation of Zen practice is zazen, a dynamic, one-pointed and penetrating practice that offers a time-tested way of diving beneath the waves of thought, into the radiant depths of our being. It is the way demonstrated by the Buddha himself some 2500 years ago in India, sitting in the lotus posture beneath the Bo tree - the way that erupted into his Supreme Enlightenment. Out of this earthshaking experience arose the vast body of Buddhist scriptures, with their core teaching of the intrinsic perfection, dignity and wonder of all existence.
But 'Zen' can also refer to the very Essence of existence itself. In this sense, Zen transcends all religious boundaries: pointing directly to the deepest truth of human nature, it is the core of every genuine spiritual teaching. For this reason, spiritual awakenings by people in every tradition and in every era share strikingly similar features and insights.
It is not necessary for anyone (including Buddhists) to believe in Buddha or his teaching if they do not wish to. It is up to the individual to understand what he teaches.