Go to a quiet place, sit in lotus posture, and place one hand on top of the other.
Without leaning to either side, bring your ears into alignment with your shoulders.
Open your eyes only halfway and fix your attention on the tip of your nose.
Rest your tongue on the roof of your mouth.
Throw away your body and your life.
Looking from the inside, your self has no mind.
Forget also about your connections with others.
Looking from the outside, there is no mind anywhere to be found.
If random thoughts should occur to you unexpectedly, let them go straight away. Do not follow them. This is the essential technique of zazen.
~ Mugai Nyodai (d. 1298)
( Zen Sourcebook Traditional Documents from China, Korea, and Japan )