The goodness or virtue of a person. In the thought of Plato and Aristotle virtue is connected with performing a function (ergon), just as an eye is good if it performs its proper function of vision. This is its telos or purpose (see also teleology). Aretē is therefore identified with what enables a person to live well or successfully, although whether virtue is then just a means to successful life or is an essential part of the activity of living well becomes controversial. According to Aristotle the various virtues consist in knowing how to strike a mean between opposing vices of excess and defect. Greek thought also paves the way for the Christian ideal that the fullest development of aretē for human beings consists in a self-sufficient life of contemplation and wisdom. The Sanskrit word kusala is used in Buddhism to represent the same association of goodness with the skill of being a good human being.