Of every continuous entity that is divisible into parts it is possible to take the larger, the smaller, or an equal part, and these parts may be larger, smaller, or equal1 either in relation to the entity itself, or in relation to us. The “equal” part is something median between the excess and deficiency. By the median of an entity I understand a point equidistant from both extremes, and this point is one and the same for everybody. By the median relative to us I understand an amount neither too large nor too small, and this is neither one nor the same for everybody. To take an example: if ten is many and two is few, six is taken as the median in relation to the entity, for it exceeds and is exceeded by the same amount, and is thus the median in terms of arithmetical proportion. But the median relative to us cannot be determined in this manner: if ten pounds of food is much for a man to eat and two pounds little, it does not follow that the trainer will prescribe six pounds, for this may in turn be much or little for him to eat; it may be little for Milo2 and much for someone who has just begun to take up athletics. The same applies to running and wrestling. Thus we see that an expert in any field avoids excess and deficiency, but seeks the median and chooses it - not the median of the object but the median relative to us.
If this, then, is the way in which every science perfects its work, by looking to the median and by bringing its work up to that point - and this is the reason why it is usually said of a successful piece of work that it is impossible to detract from it or to add to it, the implication being that excess and deficiency destroy success while the mean safeguards it (good craftsmen, we say, look toward this standard in the performance of their work) - and if virtue, like nature, is more precise and better than any art, we must conclude that virtue aims at the median. I am referring to moral virtue: for it is moral virtue that is concerned with emotions and actions, and it is in emotions and actions that excess, deficiency, and the median are found. Thus we can experience fear, confidence, desire, anger, pity, and generally any kind of pleasure and pain either too much or too little, and in either case not properly. But to experience all this at the right time, toward the right objects, toward the right people, for the right reason, and in the right manner - that is the median and the best course, the course that is a mark of virtue.
Similarly, excess, deficiency, and the median can also be found in actions. Now virtue is concerned with emotions and actions; and in emotions and actions excess and efficiency miss the mark, whereas the median is praised and constitutes success. But both praise and success are signs of virtue or excellence. Consequently, virtue is a mean in the sense that it aims at the median. This is corroborated by the fact that there are many ways of going wrong, but only one way which is right - for evil belongs to the indeterminate, as the Pythagoreans imagined, but good to the determinate. This, by the way, is also the reason why the one is easy and the other hard: it is easy to miss the target but hard to hit it. Here, then, is an additional proof that excess and deficiency characterize vice, while the mean characterizes virtue: for “bad men have many ways, good men but one.”3
We may thus conclude that virtue or excellence is a characteristic involving choice, and that it consists in observing the mean relative to us, a mean which is defined by a rational principle, such as a man of practical wisdom would use to determine it. It is the mean by reference to two vices: the one of excess and the other of deficiency. It is, moreover, a mean because some vices exceed and others fall short of what is required in emotion and in action, whereas virtue finds and chooses the median. Hence, in respect of its essence and the definition of its essential nature virtue is a mean, but in regard to goodness and excellence it is an extreme. (II, 1106b)
 It is impossible to capture in English the overtone these three words carry. They can also mean “too large,” “too small,” and “fair.”
 Milo of Croton, said to have lived in the second half of the sixth century B.C., was a wrestler famous for his remarkable strength.
 The author of this verse is unknown.
Aristotle. Nicomachean Ethics. Trans. Martin Ostwald. Prentice Hall, 1999.
Works and Days