zazengi-dogenDogen Zenji (1200-1253) is known as the founder of the Soto school of Zen in Japan. As a young man he travelled to China where he received Dharma transmission from Tiantong Rujing. On his return to Japan, Dogen revitalised the practice of zazen. We still look to his recommendations today. Here is an extract from Fukanzazengi (Universal Recommendation for Zazen):

‘Straighten your body and sit upright, leaning neither left nor right, neither forward nor backward. Align your ears with your shoulders and your nose with your navel. Rest the tip of your tongue against the front of the roof of your mouth, with teeth and lips together both shut. Always keep your eyes open, and breathe softly through your nose. Once you have adjusted your posture, take a breath and exhale fully, rock your body right and left, and settle into steady, immovable sitting. Think of not thinking. Not thinking: What kind of thinking is that? Letting thoughts go. This is the essential art of zazen. Zazen is not a meditation technique. It is simply the Dharma gate of joyful ease, it is practicing the realization of the boundless Dharma way.’

source: http://antaiji.org/en/classics/fukanzazengi/