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.
There is a story of Rikyu which well illustrates the ideas of cleanliness entertained by the tea masters. Rikyu was watching his son Shoan as he swept and watered the garden path. "Not clean enough," said Rikyu, when Shoan had finished his task, and bade him try again. After a weary hour the son turned to Rikyu: "Father, there is nothing more to be done. The steps have been washed for the third time, the stone lanterns and the trees are well sprinkled with water, moss and lichens are shining with a fresh verdure; not a twig, not a leaf have I left on the ground"
"Young fool," chided the tea master, "that is not the way a garden path should be swept. "Saying this, Rikyu stepped into the garden, shook a tree and scattered over the garden gold and crimson leaves, scraps of the brocade of autumn! What Rikvu demanded was not cleanliness alone, but the beautiful and the natural also.