Katsuki Sekida quotes:

What has happened by chance is often difficult to repeat when it is sought deliberately. Chance is a genius.

The occurrence of an evil thought is an affliction; not to continue it is the remedy.

You know the Zen question, 'The Bodhisattva of Great Mercy' has a thousand hands and a thousand eyes; 'which is the true eye?' I could not understand this for a long time. But the other day, when I looked at the pine trees bending before the cold blasts from the mountain, I suddenly realized the meaning. You see, all the boughs, branches, twigs, and leaves simultaneously bend to the wind with tremendous vigor.

Zen is not, in my view, philosophy or mysticism. It is simply a practice of readjustment of nervous activity. That is, it restores the distorted nervous system to its normal functioning.