Zen teaches the practice of zazen, sitting in meditative absorption as the shortest, but also steepest path to enlightenment. Unlike many other forms of meditation, the aim of zazen is not to concentrate the mind on a specific object, but to point the mind toward liberation from all mental habits. During zazen, discursive thinking decreases, and the mind becomes stilled, like a clear pool of water. It is said that, during zazen, one can experience unordinary physical sensations and visual perceptions. However, the aim of zazen is not to chase after these experiences which arise during various stages of progress. The aim of zazen is to exist in the true nature of the mind, in which distinguishments between "I" and "not-I" no longer exist.
"In its purest form zazen is dwelling in a state of thought-free, alertly wakeful attention, which, however, is not directed toward any object and clings to no content (shikantaza). If practiced over a long period of time with persistence and devotion, zazen brings the mind of the sitter to a state of totally contentless wakefulness, from which, in a sudden breakthrough of enlightenment, he can realize his own true nature or buddha-nature, which is identical with the nature of the entire universe."
- Shambhala Dictionary of Buddhism and Zen.
Advanced zazen practitioners do not
have to be sitting in order to practice. It is claimed that a master can
do zazen while engaged in any activity. The emptiness experienced in zazen
should not be confused with a mere blank mind; if this were the case, directed
actions, such as standing, eating, or walking would be impossible.