"Approximation is also one of the stones by whose aid we construct the edifice of common sense.
"Concerning the calculations of probabilities, the application of approximation will allow us to estimate the capacity or the probable duration of things.
"We can not say positively whether a man will live a definite number of years but we can affirm that he will never live until he is two hundred.
"There are, for approbation, certain known limits which serve as a basis for the construction of reasoning, inspired by common sense.
"It can be affirmed, in a positive way, that, if the trunk of a tree were floating easily, without sinking to the bottom of the water, it would not float the same if thirty men were to ride astride of it.
"The initial weight of the tree permits it to maintain itself on the surface; but if it be increased to an exaggerated total, we can, without hesitation, calculate indirectly the moment when it will disappear, dragging with it the imprudent men who trusted themselves to it.
"Everything in life is a question of approximation.
"The house which is built for a man will be far larger than the kennel, destined to shelter a dog, because the proportions have been calculated, by approximation, according to the relative difference between the stature of the human and canine species.
"Clothing is also suited to the temperature.
"One naturally thinks that, below a certain degree of cold, it is necessary to change light clothes for those made of thicker material.
"As with the majority of the constructive elements of common sense, approximation is always based on experience.
"It draws its conclusions from the knowledge of known limitations, whose affirmation serves as a basis for the argument which determines deduction in a most exact manner.
"Experience itself depends on memory, which permits us to recall facts and to draw our conclusions from them, on which facts reasoning is based."
The Shogun does not fail to draw our attention to the difference between experience and experimentation.
"This last," said he, "only serves to incite the manifestation of the first.
"It consists of determining the production of a phenomenon whose existence will aid us in establishing the underlying principles of an observation which interprets the event.
"That is what is called experience.
"Comparison is a mental operation which permits us to bring things that we desire to understand to a certain point.
"It is comparison which has divided time according to periods, which the moon follows during its entire length.
"It is by comparing their different aspects and by calculating the duration of their transformations, that men have been able to divide time as they do in all the countries of the world.
"The science of numbers is also born of comparison, which has been established between the quantities that they represent.
"This is the art of calculating the differences existing between each thing, by determining the relativeness of their respective proportions.
"Comparison acts on the mind automatically, as a rule.
"It is indispensable to the cultivation of common sense, for it furnishes the means of judging with full knowledge of all the circumstances.
"Analysis is an operation, which consists of separating each detail from the whole and of examining these details separately, without losing sight of their relationship to the central element.
"Analysis of the same object, while being scrupulously exact, can, however, differ materially in its application, according to the way that the object is related to this or that group of circumstances.
"There are, however, immutable things.
"For example: the letters of the alphabet, the elementary sounds, the colors etc., etc.
"It suffices to quote only these three elements; one can easily understand that the most elaborate manuscript is composed of only a definite number of letters always repeating themselves, whose juxtaposition forms phrases, then chapters, and finally the complete work.
"Music is composed only of seven sounds whose different combinations produce an infinite variety of melodies.
"Elementary colors are only three in number.
"All the others gravitate around them.
"Therefore, these same letters, these same notes, these same colors, according to their amalgamation, can change in aspect and cooperate in the production of different effects.
"The same letters can express, according to the order in which they are placed, terror or confidence, joy or grief.
"The same is true of notes and colors.
"Common sense ought then, considering these rules, to know how to analyze all the details and, having done this, to coordinate and to classify them, in order to distinguish them easily.
"Coordination and classification form an integral part of common sense."
And Yoritomo, who delights in reducing the most complex questions to examples of the rarest simplicity, says to us:
"I am supposing that one person says to another, I have just met a negro.
The interlocutor, as well as he who mechanically registers this fact, without thinking, gives himself up to analysis and to coordination which always precedes synthesis.
"Without being aware of this mental action, their minds will be occupied first with the operations of perception then of classification.
"This negro was a man of a color which places him in a certain group of the human race.
"It is always thus that common sense proceeds, its principal merit being to know how to unite present perceptions with those previously cognized, then to understand how to coordinate them so as to be able to group them concretely, that is to say, to synthesize them.
"Destination is defined as the purpose or object, born of deduction and of classification.
"Destination does not permit of losing sight of the end which is proposed.
"It allows the consideration of the purpose to predominate always, and directs all actions toward this purpose, these actions being absolutely the demonstrations of this unique thought.
"Habits, acquired in view of certain realizations, ought to be dropt from the moment the purpose is accomplished, or that it is weakened."
It is by absolutely perpetuating those habits, whose pretext has disappeared, that one sees the achievement of certain actions which have been roughly handled by common sense.
"There are," again says the philosopher, "certain customs, whose origin it is impossible to remember; at the time of their birth, they were engendered by necessity, but even tho their purpose be obliterated, tradition has preserved them in spite of everything, and those who observe them do not take into consideration their absurdity.
"People of common sense refrain from lending themselves to these useless practises, or, if they consent to allow them a place in their thoughts it is that they attribute to them some reason for existence, either practical or sentimental."
Direction is indicated by circumstances, by environment, or by necessity.