In places stamped with the monotony and repetition of sameness you move, but in moving you seem to have gotten nowhere.
North is the same as south, or east as west. Sometimes north, south, east and west are all alike, as they are when you stand within the grounds of a large project. It takes differences—many differences—cropping up in different directions to keep us oriented.
Scenes of thoroughgoing sameness lack these natural announcements of direction and movement, or are scantly furnished with them, and so they are deeply confusing. This is a kind of chaos.
Mystery exists in the mind, not in reality. If I am ignorant about a phenomenon, that is a fact about my state of mind, not a fact about the phenomenon itself. All the more so if it seems like no possible answer can exist: Confusion exists in the map, not in the territory. Unanswerable questions do not mark places where magic enters the universe. They mark places where your mind runs skew to reality.
It is related that the bodhisattva Manjusri was once standing at the gate, and seeing him, Shakyamuni Buddha called to him, "Manju, Manju, why don't you come inside the gate?"
Manjusri replied, "I don't see anything outside the gate."
When you once attain true self-realization, these barriers disappear in an instant as though they were nothing but mirages, and you will find that from the very beginning you have always been in a world where there is neither inside nor outside. That is what "gateless" means. Therefore, all koans are impassable barriers for those who are unenlightened, but for the enlightened there is no gate at all. They can come and go quite freely.
One day, as Kyogen was clearing the undergrowth, a pebble bounced off the tip of his broom and resounded against a bamboo tree. Hearing the sound, he suddenly experienced great enlightement. The first stanza of the poem he composed on this occasion is very famous:
One striking sound,
and I have forgotten all I knew.