"It is thought which distinguishes men from animals, who have only instinct to guide them. "It can be admitted, however, that this instinct is a kind of obscure thought for these inferior beings, from which reflection is eliminated, or, at least, reveals itself only as a vassal of material appetite. "But with creatures who have intelligence, thought is a superior faculty, which aids the soul to free itself from the bondage of vulgar and limited impressions. "When perception, memory, and thought unite to form judgment, activity of mind will become necessary, in order to accelerate the production of ideas in extending the field of imagination. "Moral inertia is the most deplorable of all defects; it retards intellectual growth and hinders the development of personality. "It is, in this understanding, the enemy of common sense, for it will admit voluntarily a reasoning power, existing per se, rather than make the necessary effort which will set free the truth and constitute an individual opinion. "Vulgarity is, then, almost always the sign of mental sloth. "It is not infrequent to see a mind of real capacity fall into error, where an intelligence of mediocre caliber asserts its efficiency. Indifference is the most serious obstacle to the attainment of judgment. "Common sense demands a keen alertness of understanding, placed at the disposal of a reflection which appears at times slow of action, but which is long in being manifested only because of the desire to surround itself by all the guaranties of truth concerning the object in question. "The fifth blade of the fan is the quality of deduction--the most solid basis for the judgments which are formed by common sense. "By deduction we are able to solve all relative questions with perfect accuracy. "It is by abstracting reckless contingencies, and by relying only upon the relativeness of facts, that we can succeed in discovering the truth that there are too many representations as to these facts. "Deduction is the great support of mental weakness. It helps in discerning proportions, possibilities, even as it helps in skilfully avoiding the fear of error." We shall have occasion to speak more at length of deduction, for Yoritomo devotes many pages to it. We shall, then, defer to a future chapter the interesting developments that he discloses on this subject, and we shall continue to study the fan of common sense with him. "Foresight," he continues, "is rightly looked upon as one of the indispensable elements in cultivating common sense. "The faculty of foresight always accompanies common sense, in order to strengthen its qualities of skill and observation. "One must not confound, as many people are tempted to do, foresight and conjecture. "The first consists in taking great care to prevent the repetition of unhappy facts which have already existed.