"On Virtue and Vice" is a treatise in ethics. It offers a systematic and historical study of the Doctrine of the Mean. The book argues for a triadic approach to ethical notions (for example, Goodness and two forms of Badness and Justice and two forms of Injustice). The approach of the book is intertwined with a critical study of the relevant thought both of Western thinkers (Pythagoras, Plato, Aristotle, Thomas Aquinas and David Hume) and also of Eastern thinkers (Confucius, Mencius and Chu Hsi). A further aim of the book is to apply the Doctrine to contemporary life.