The mind of zazen is the mind of the morning of the world, before the passions, before the flames rise. To awaken with the day which is dawning. Be careful not to let your mind take hold of the usual preoccupations. Maintain the calm of the morning, of the rising day: the mind of the morning of the world.
Just stand up straight and still, doing nothing else. At that moment, as the night slips imperceptibly into the day, your mind awakens.
The mind of the morning of the world is the original mind, the calm mind, before the flames of passions rise, or after they are extinguished. Sometimes it is called the spirit of nirvana, when we appease the flames of our anger, when we understand the roots of our anger, then the anger turns into compassion. This is the experience of nirvana- nirvana meaning the extinction of all flames, all afflicting passions, all toxic flows of thoughts.
Also, in zazen, if your mind starts to wander, do not follow it in its wanderings. Maintain yourself in the reality where the night transforms itself into day, or the day transforms itself into night; where birth transforms itself into death, where death transforms itself into birth. Because of course in the ultimate reality, when we let go of all our conceptions, there is neither birth nor death, but a permanent continuum, a continuous transformation.
When we stand before words appear, we experience all things: this is called nirvana, the extinction of all that causes suffering. Birds plunge into the sky, fish glide in the ocean, wise men frolic in nirvana. So don’t move. Don’t cling to your little difficulties. Keep calm and stillness, with your eyes wide open. Let all things appear and disappear.