The third infirmity of mind is caused by the levity of nature; for many men are of such light fancy that in all their arguments they go astray, and even when they make a syllogism and have concluded, from that conclusion they fly off into another, and it seems to them most subtle argument. They start not from any true beginning, and truly they see nothing true in their imagination. Of those men the Philosopher says that it is not right to trouble about them, or to have business with them, saying, in the first book of Physics, that against him who denies the first postulate it is not right to dispute. And of such men as these are many idiots, who may not know their A B C, and who would wish to dispute in Geometry, in Astrology, and in the Science of Physics. Also through sickness or defect of body, it is possible for the Mind to be unsound or sick; even as through some primal defect at birth, as with those who are born fools, or through alteration in the brain, as with the madmen. And of this mental infirmity the Law speaks when it says: "In him who makes a Will or Testament, at the time when he makes the Will or Testament, health of mind, not health of body, is required." But to those intellects which from sickness of mind or body are not infirm, but are free, diligent, and whole in the light of Truth, I say it must be evident that the opinion of the people, which has been stated above, is vain, that is, without any value whatever, worthless. Afterwards the Song subjoins that I thus judge them to be false and vain; and this it does when it says, "Sound intellect reproves their words As false, and turns away." And afterwards I say that it is time to demonstrate or prove the Truth; and I say that it is now right to state what kind of thing true Nobility is, and how it is possible to know the man in whom it exists; and I speak of this where I say: And now I seek to tell As it appears to me, What is, whence comes, what signs attest A true Nobility. CHAPTER XVI. "The King shall rejoice in God, and all those shall be praised who swear by him, for closed is the mouth of those who speak wicked things." These words I can here propound in all truth; because each true King ought especially to love the Truth. Wherefore it is written in the Book of Wisdom, "Love the Light of Wisdom, you, who stand before, the people," and the Light of Wisdom is this same Truth. I say, then, every King shall rejoice that the most false and most injurious opinion of the wicked and deceitful men who have up to this time spoken iniquitously of Nobility is confuted.