Metaphysics investigates principles of reality transcending those of any particular science. Cosmology and ontology are traditional branches of metaphysics. It is concerned with explaining the fundamental nature of being and the world. Someone who studies metaphysics can be called either a "metaphysician" or a "metaphysicist".
The word derives from the Greek words μετά (metá) (meaning "beyond" or "after") and φυσικά (physiká) (meaning "physical"), "physical" referring to those works on matter by Aristotle in antiquity. The prefix meta- ("beyond") was attached to the chapters in Aristotle's work that physically followed after the chapters on "physics", in posthumously edited collections. Aristotle himself did not call these works Metaphysics. Aristotle called some of the subjects treated there "first philosophy".
A central branch of metaphysics is ontology, the investigation into what types of things there are in the world and what relations these things bear to one another. The metaphysician also attempts to clarify the notions by which people understand the world, including existence, objecthood, property, space, time, causality, and possibility.
Before the development of modern science, scientific questions were addressed as a part of metaphysics known as "natural philosophy"; the term "science" itself meant "knowledge" of epistemological origin. The scientific method, however, made natural philosophy an empirical and experimental activity unlike the rest of philosophy, and by the end of the eighteenth century it had begun to be called "science" in order to distinguish it from philosophy. Thereafter, metaphysics became the philosophical enquiry of a non-empirical character into the nature of existence. Thus the original situation of metaphysics being integral with (Aristotelian) physics and science, has, in the West, become reversed so that scientists often consider metaphysics antithetical to the empirical sciences. .
