The next rule is that if desires are regulated too severly or not severly enough then a problem may come up. The third rule, in which Aristotle speaks of, is that character traits are equal to desire. It has nothing to do with nature in the respect that nature cannot form habits. We as a people are adapted by nature to receive desires and they are perfected through habitual practice. Aristotle explains that it is through practice that men become good or bad at a subject. He uses an example of a builder. A builder becomes one by building, through this the man realizes whether he is a good or bad builder. If this were not true, Aristotle says that there would be no need for teachers and that people would be born good or bad at a trade. .
He makes a comparison between the builder and virtues because it is by transactions with other men that we become just or unjust. Also stated was our presence in danger will give men habits towards cowardice or bravery. Aristotle speaks about childhood and its effect on virtues by saying, "It makes no small difference, then, whether we form habits of one kind or of another from our very youth;.it makes all the difference."" (Aristotle, p. 102) Moral virtue relates to happiness and flourishing because when man makes the correct decisions by practicing the habits that enable good virtues a man will become happy and flourish. He believes that virtue is the only way to experience eudaimonia and that everyone seeks it and it is the only way to achieve "true- success.
Aristotle's Eudaimonia is the main idea of The Doctrine of the Mean. This is a concept that deals with both intellectual and moral virtue. The Doctrine of the Mean states that man cannot obtain the flourishing and happiness of Eudaimonia if he is at the the excess or the deficiency of the virtue. These extremes lead to a loss of happiness. To find Eudaimonia, one must find the intermediate of the excess and deficiency, also known as the mean.