The Nicomachean Ethics (ˌnaɪkɒməˈkiən; ˌnɪkəməˈkiən; Ἠθικὰ Νικομάχεια, Ēthika Nikomacheia) is Aristotle's best-known work on ethics: the science of the good for human life, that which is the goal or end at which all our actions aim. It consists of ten subsections, referred to as books or scrolls, and is closely related to Aristotle's Eudemian Ethics. The work plays a pre-eminent role in explaining Aristotelian ethics. The theme of the work is a Socratic question previously explored in the works of Plato, Aristotle's friend and teacher, about how men should best live.