Directions given by a Zen master (from a 1265 text):
The Bodhisattva who disciplines himself in Prajna should first of all awaken a great compassionate heart, make great universal vows, and thoroughly be versed in all Samadhis, in order to deliver all beings; for the Bodhisattva does not seek emancipation for his own benefit. Let him renounce all external relations and put a stop to all worldly doings, so that his mind and body becoming one they can be kept, moving or sitting, in perfect harmony with each other. His food should be regulated, neither too much nor too little; and his sleep also should be moderate, neither too long nor too short.
When he wishes to practise meditation, let him retire into a quiet room where he prepares a thick well-wadded cushion for his seat, with his dress and belt loosely adjusted about his body. He then assumes his proper formal posture. He will sit with his legs fully crossed, that is, place the right foot over the left thigh and the left foot over the right thigh. Sometimes the half-cross-legged posture is permitted, in which case simply let the left leg rest over the right thigh. Next, he will place the right hand over the left leg with its palm up and over this have the left hand, while the thumbs press against each other over the palm.
He now raises the whole body slowly and quietly, moves it repeatedly to the left and to the right, backward and forward, until the proper seat and straight posture are obtained. He will take care not to lean too much to one side, either left or right, forward or backward; his spinal column stands erect with the head, shoulders, back, and loins each properly supporting others like a chaitya. But he is cautious not to sit too upright or rigidly, for he will then feel uneasy before long. The main thing is to have the ears and shoulders, nose and navel stand to each other in one vertical plane, while the tongue rests against the upper palate and the lips and teeth are firmly closed. Let the eyes be slightly opened in order to avoid falling asleep.
When meditation advances the wisdom of this practice will grow apparent. Great masters of meditation from of old have kept their eyes open. Yuan-t’ung, the Zen master of Fa-yun, has also had a strong opinion against the habit of closing the eyes, and called such practisers “dwellers of the skeleton cave in the dark valley”. There is a deep sense in this, which is well understood by those who know. When the position is steadied and the breathing regular, the practiser will now assume a somewhat relaxed attitude. Let him not be concerned with ideas of good or bad. When a thought arises let him bring it into awareness; brought into awareness, the thought will vanish. When the exercise is kept up steadily and for a sufficient length of time, disturbing thoughts will naturally cease to arise [having been released] and there will prevail a state of oneness. This is the technique of practising meditation.
Meditation is the road leading to peace and happiness. The reason why there are so many people who grow ill is because they do not know how to prepare themselves duly for the exercise. If they well understand the directions as given above, they will without straining themselves too much acquire not only the lightness of the body but the briskness of spirit, which finally brings about the clarification of the consciousness. The understanding of the Dharma will nourish the spirit and make the practiser enjoy the pure bliss of tranquillity.
If he has already a realization within himself, his practice of meditation will be like a dragon getting into water, or a tiger crouching against a hillside. In case he has yet nothing of self-realization, the practice will be like fanning a flame; there should not be too much effort [lest one extinguish it]. Only let him not too easily be deceived as to what he may regard as self-realization.
When there is an enhanced spiritual quality, there is much susceptibility to the Evil One’s temptation, which comes in every possible form both agreeable and disagreeable. Therefore the practiser must have his consciousness rightly adjusted and well in balance; then nothing will prevent his advancement in meditation. Concerning various mental aberrations worked out by the Evil One, a detailed treatment is given in The Leng-yen Sutra (Surangama, fas. VIII), the T’ien-tai Chih Kwan, and Keui-feng’s Book on Practice and realisation. Those who wish to prepare themselves against untoward events should be well informed of the matter.
When the practiser wants to rise from meditation, let him slowly and gently shake his body and quietly rise from the seat; never let him attempt to rise suddenly. After the rising let him always contrive to retain whatever mental power he has gained by meditation, as if he were watching over a baby; for this will help him in maturing the power of concentration.
Originally in Regulations of the Meditation Hall, compiled by Pai-chang (720-814) the founder of the Zen monastery in China.
Suzuki, D. T. (1953). Essays in Zen Buddhism (Second Series). London: Rider and Company (pp. 327-328).