Whatever we learn to do, we learn by actually doing it; men come to be builders, for instance, by building, and harp players by playing the harp. In the same way, by doing just acts we come to be just; by doing self-controlled acts, we come to be self-controlled ; and by doing brave acts, we become brave.
If then, as we say, good craftsmen look to the mean as they work, and if virtue, like nature, is more accurate and better than any form of art, it will follow that virtue has the quality of hitting the mean. I refer to moral virtue [not intellectual], for this is concerned with emotions and actions, in which one can have excess or deficiency or a due mean.
Those who assert that the mathematical sciences say nothing of the beautiful or the good are in error. For these sciences say and prove a great deal about them; if they do not expressly mention them, but prove attributes which are their results or definitions, it is not true that they tell us nothing about them. The chief forms of beauty are order and symmetry and definiteness, which the mathematical sciences demonstrate in a special degree.
It must not be supposed that happiness will demand many or great possessions; for self-sufficiency does not depend on excessive abundance, nor does moral conduct, and it is possible to perform noble deeds even without being ruler of land and sea: one can do virtuous acts with quite moderate resources. This may be clearly observed in experience: private citizens do not seem to be less but more given to doing virtuous actions than princes and potentates. It is sufficient then if moderate resources are forthcoming; for a life of virtuous activity will be essentially a happy life.
But obviously a state which becomes progressively more and more of a unity will cease to be a state at all. Plurality of numbers is natural in a state; and the farther it moves away from plurality towards unity, the less of a state it becomes and the more a household, and the household in turn an individual.
Money was intended to be used in exchange, but not to increase at interest. And this term interest, which means the birth of money from money, is applied to the breeding of money because the offspring resembles the parent. Wherefore of all modes of getting wealth this is the most unnatural.
Where some people are very wealthy and others have nothing, the result will be either extreme democracy or absolute oligarchy, or despotism will come from either of those excesses.