In order not to leave any traces, when you do something, you should do it with your whole body and mind; you should be concentrated on what you do. Y… - Shunryu Suzuki

Concentration is not to try hard to watch something... Concentration means freedom... In zazen practice we say your mind should be concentrated on your breathing, but the way to keep your mind on your breathing is to forget all about yourself and just to sit and feel your breathing.

As long as you have rules, you have a chance for freedom. To try to obtain freedom without being aware of the rules means nothing.

We say, “To hear the sound of one hand clapping.” Usually the sound of clapping is made with two hands, and we think that clapping with one hand makes no sound at all. But actually, one hand is sound. Even though you do not hear it, there is sound. If you clap with two hands, you can hear the sound. But if sound did not already exist before you clapped, you could not make the sound. Before you make it there is sound. Because there is sound, you can make it, and you can hear it. Sound is everywhere. If you just practice it, there is sound. Do not try to listen to it. If you do not listen to it, the sound is all over. Because you try to hear it, sometimes there is sound, and sometimes there is no sound. Do you understand? Even though you do not do anything, you have the quality of zazen always. But if you try to find it, if you try to see the quality, you have no quality.