Virtues are in vogue. Their alleged loss is lamented in a cultural critique, just as a revival of entirely heterogeneous catalogs of virtues is demanded. But what exactly is a virtue? How do virtues and vices relate to each other? Does virtue contribute to the happiness of the virtuous, or is the virtuous person rather the fool? Do virtues presuppose one another, or can they be possessed independently? Christoph Halbig addresses these questions within the framework of a comprehensive ontology of virtue and subjects the effectiveness of this category in ethics to a critical examination.