The important lesson to draw from Aristotle’s Doctrine of the Mean is that virtue consists of finding an appropriate middle ground between two extremes. As such, each virtue has not one opposite but two. The opposite of courage is both cowardice and rashness, for example. This idea that there are two opposites for every virtue goes against much of the received wisdom of Aristotle’s time, including Plato’s writings on virtue. It also emphasizes the importance of moderation: we achieve virtue by finding a middle ground, not by aiming for an extreme. Where exactly this middle ground lies, however, is less obvious. Aristotle repeats a number of times that his table presents only a rough approximation and that virtues lie closer to one vice than another to different extents for different people. The Table of Virtues just presented is not intended as a set of exact rules. On the contrary, Aristotle argues that a truly virtuous person will naturally be inclined to behave appropriately and will have no need of rules.

Aristotle is clear that we arrive at moral virtue primarily through practice and that the value of studying ethical texts such as the one he has written is limited. This view makes sense when we consider that moral virtue is not essentially different from other forms of excellence as far as the Greeks are concerned. If we want to achieve excellence in rock climbing, for instance, it helps to study texts that show us how to improve our technique, but we can’t make any significant improvements except by getting on a rock wall and practicing. Analogously, it helps to read texts like the Nicomachean Ethics to get a clearer understanding of moral virtue, but the only way to become more virtuous is through practice. We can only become more courageous by making a point of facing down our fears, and we can only become more patient by making a habit of controlling our anger. Since practice, not study, is the key to becoming virtuous, Aristotle takes a strong interest in the education of the young. He perceives that there is only so much we can do to improve a nasty adult, and we can more easily mold virtuous youths by instilling the proper habits in them from a young age.

Aristotle calls happiness an “activity,” which distinguishes his conception of happiness both from our modern conception of happiness and from virtue, which Aristotle calls a “disposition.” We tend to think of happiness as an emotional state and hence as something we are, rather than as something we do. The Greek word generally translated as “happiness” is eudaimonia, and it can equally be rendered as “success” or “flourishing.” People who are eudaimon are not in a particular emotional state so much as they are living successfully. While happiness is the activity of living well, virtue represents the potential to live well. Excelling in all the moral virtues is fine and good, but it doesn’t ensure our happiness unless we exercise those virtues. Courageous people who never test their courage by facing down fear have virtue, but they are not happy. Aristotle illustrates this distinction between happiness and virtue by saying that the best athletes only win at the Olympic Games if they compete. A virtuous person who does not exercise virtue is like an athlete who sits on the sideline and watches. Aristotle has a proactive conception of the good life: happiness waits only for those who go out and seize it.