What is virtue according to Plato and Aristotle?

According to Plato, virtue is knowledge that leads to a harmonious relationship between different parts of the soul, namely reason, spirit, and desire. For Aristotle, virtue is the mean between two extremes, a state of character that allows a person to act and feel in the right way at the right time and to the right extent. Both agree that virtue is essential for achieving happiness and living a virtuous life.