And since in all these voluntary operations there is some equity to preserve and some iniquity to shun--which equity may be lost through two causes, either through not knowing what it is, or through not wishing to follow it--the written Reason, the Law, was invented, both to point it out to us and to command its observance.

Wherefore Augustine says: "If men could know this, that is, Equity, and knowing it would obey it, the written Reason, the Law, would not be needful." And therefore it is written in the beginning of the old Digests or Books of the Civil Law: "The written Reason is the Art of Goodness and of Equity." To write this, to show forth and to enforce this, is the business of that Official Post of which one speaks, that of the Emperor, to whom, as has been said, in so far as our own operations extend, we are subject, and no farther.

For this reason in each Art and in each trade the artificers and the scholars are and ought to be subject to the chief and to the master of their trades and Art: beyond their callings the subjection ceases, because the superiority ceases.
So that it is possible to speak of the Emperor in this manner, if we will represent his office figuratively, and say that he may be the rider of the Human Will, of which horse how it goes without its rider through the field is evident enough, and especially in miserable Italy, left without any means for its right government.

And it is to be considered that in proportion as a thing is more fit for the Master's art, so much the greater is the subjection; for the cause being multiplied, so is the effect multiplied.

Wherefore it is to be known that there are things which are such pure or simple Arts that Nature is their instrument; even as rowing with an oar, where the Art makes its instrument by impulsion, which is a natural movement; as in the threshing of the corn, where the Art makes its instrument, which is a natural quality.