Here's a brief greatest hits compilation, of sorts, from some of his many books:
From Nature, Man and Woman:
For the point is not, in our accustomed egocentric mode of thinking, that it would be good to return to our original integrity with nature. The point is that it is simply impossible to get away from it, however vividly we may imagine we have done so. Similarly, it is impossible to experience the future and not experience the present. But trying to realize this is another attempt to experience the future. Some logician may object that this is a merely tautological statement which has no consequence, and he will be right. But we are not looking for a consequence. We are no longer saying, "So what?" to everything, as if the only importance of our present experience were in what it is leading to, as if we should constantly interrupt a dancer, saying, "Now just where are you going, and what, exactly, is the meaning of all these movements?"
The Meaning of Happiness:
We have a proverb that to travel well is better than to arrive, which comes close to the Oriental idea. Wisdom does not consist in arriving at a particular place, and no one need imagine that it is necessarily obtained by climbing a ladder whose rungs are the successive stages of psychological experience. That ladder has no end, and the entrance to enlightenment, wisdom or spiritual freedom may be found on any one of its rungs. If you discover it, it does not mean that you will not have to go on climbing the ladder; you must go on climbing just as you must go on living. But enlightenment is found by accepting fully the place where you stand now.
The notion that human sanity has a good deal to do with self-restraint has persisted for many thousands of years, and has had some very wise exponents. But it has usually had an end in view—a temporal, future end—some sort of pie in the sky. No one can really abstain, however; no one can effectively overcome the mad greed of anxiety, until he has realized that the future is a mirage which does not contain the answer to anything. The true ascetic is not forcing himself; he is just acting naturally in accordance with reality as he sees it.
The Wisdom of Insecurity:
The notion of a separate thinker, of an "I" distinct from the experience, comes from memory and from the rapidity with which thought changes. It is like whirling a burning stick to give the illusion of a continuous ring of fire. If you imagine that memory is a direct knowledge of the past rather than a present experience, you get the illusion of knowing the past and the present at the same time. This suggests that there is something in you distinct from both the past and present experiences. You reason, "I know this present experience, and it is different from that past experience. If I can compare the two, and notice that experience has changed, I must be something constant and apart." But as a matter of fact, you cannot compare this present experience with a past experience. You can only compare it with a memory of the past, which is a part of the present experience. When you see clearly that memory is a form of present experience, it will be obvious that trying to separate yourself from this experience is as impossible as trying to make your teeth bite themselves. There is simply experience. There is not someone or something experiencing experience!
Still more important, it is quite obvious to the canny observer that most Christians, including clergy and devout laity, do not really believe in Christianity. If they did, they would be screaming in the streets, taking daily full-page advertisements in the newspapers, and subscribing for the most hair-raising television programs every night of the week. Even Jehovah's Witnesses are polite and genteel in their door-to-door propaganda. Nobody, save perhaps a few obscure fanatics, is really bothered by the idea that every man is constantly haunted by an angelic fiend, more imminently dangerous and malicious than the most depraved agents of the Nazis. Most people are sinners and unbelievers, and will probably go to hell. So what? Let God worry about that one!
This Is It:
But the Westerner who is attracted by Zen and who would understand it deeply must have one indispensable qualification: he must understand his own culture so thoroughly that he is no longer swayed by its premises unconsciously. He must really have come to terms with the Lord God Jehovah and with his Hebrew-Christian conscience so that he can take it or leave it without fear or rebellion. He must be free of the itch to justify himself. Lacking this, his Zen will either be "beat" or "square", either a revolt from the culture and social order or a new form of stuffiness and respectability. For Zen is above all the liberation of the mind from conventional thought, and this is something utterly different from rebellion against convention, on the one hand, or adapting foreign conventions, on the other.
The Two Hands of God:
What this means for practical action is that we accept the standards of logic and morals, not exactly with reservations, but with a certain humor. We will try to keep them, knowing that we shall not altogether succeed. We shall commit ourselves to positions and promises as best we may, knowing always that there must be a hintergedanke—a thought far in the back of the mind which, like crossed fingers, gives us an "out" when pressed too far. We shall realize that behind our devotion to duty there is always a strong element of self-admiration, and that even in the most passionate love of others there is inevitably the aspect of personal gratification.