The primary thing when you take a sword in your hands is your intention to cut the enemy, whatever the means. Whenever you parry, hit, spring, strike or touch the enemy’s cutting sword, you must cut the enemy in the same movement. It is essential to attain this. If you think only of hitting, springing, striking or touching the enemy, you will not be able actually to cut him.
The McNamara fallacy, named for Robert McNamara, the US Secretary of Defense from 1961 to 1968, involves making a decision based solely on quantitative observations (or metrics) and ignoring all others. The reason given is often that these other observations cannot be proven.
The fallacy refers to McNamara's belief as to what led the United States to defeat in the Vietnam War—specifically, his quantification of success in the war (e.g., in terms of enemy body count), ignoring other variables.
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.