The virtues are in the middle

The cardinal virtues are four: courage, prudence, discreetness, and fairness. There are eight other moral states that either go beyond or fall short of these virtues. Spiritual people consider them as vices, but non-spiritual people consider them many times as virtues. For courage going beyond is audacity while falling short is timidity.

For prudence going beyond is deceitfulness while falling short is ignorance. For discreetness going beyond is licentiousness while falling short is foolishness. For fairness going beyond is greed while falling short is inequity and injustice. The virtues are in the middle, and not only the cardinal and natural, but the ones who are superior of any exaggeration and shortcoming, the ones that are also practical. 

St. Gregory the Sinaitis (from Philokalia and his 137 chapters On Commandments and Doctrines, Warnings and Promises; on Thoughts, Passions and Virtues)

Translated by Dr. Nick Stergiou

 http://www.orthodoxpath.org/spiritual-life/the-virtues-are-in-the-middle/