Here is a bit of GENJO KOAN, a chapter from master Dogen's Shobogenzo, in Mike Luetchford's modern interpretation:
When we feel confident that we understand reality, in fact we are far from it.
When we are actually one with reality, we often feel that something is missing.
I came across some discussions on the net about what these ideas of master Dogen might mean and here is my take on what they probably mean:
When we think we understand the truth, we are only on the intellectual level, and there, in the midst of our ideas, we miss the target.
When we are one with the truth, we can't see the whole of it. Ideally, the truth is something complete, nothing is missing, but we can never find a point of view that would provide this complete view of things. So instead of trying to find the perfect point of view, we just let it be and in this moment, just acting, we are one with reality, but beyond the ideal of completeness. The finality or definition of the truth is again something intellectual, it is something we only imagine. The truth, actually, is something we don't imagine, it is just here and now, and here and now, it doesn't seem complete to a person being one with it. So a person who is one with the truth cannot find something complete, cannot show something complete to the others.
In Buddhism we sometimes naively expect that one day we will see things completely and finally. At last everything will be clear and we will be enlightened. But people of the truth cannot experience something this rigid. Instead they experience something that is impossible to stop or grasp or limit with words.
We could also give an example of a person working in the garden, someone who has never heard of Buddhism. To a naive Buddhist, this person, focusing on trimming some bushes, is far from buddhahood, far from awakening. But such a person, just simply cutting the twigs is one with the truth. There is no celebration of the person's awakening. No gods are coming to greet the person and bow in front of him or her. There is just trimming, cutting here and now. The gardener cannot notice anything special or grand or worth mentioning. What did you do in the afternoon? I just trimmed some bushes. And now I am going to the pub to drink some beer. My husband is already waiting there for me.
When we look at a statue of Buddha, we see something splendid, someone splendid, noble sitting in a beautiful posture. But to Buddha, it is just sitting, nothing else. Just a simple action in the present. No celebration is necessary. Yet in Buddhist literature, awakening or sitting in Buddha's posture is often celebrated. However, it is rather the celebration that seems splendid and complete. The thing being celebrated is usually forgotten in all the marvelous display of colors and lights.