Metaphysics is a branch of philosophy concerned with explaining the essence of things, of the fundamental nature of being and the world and the principles that organize the universe. Metaphysics is supposed to answer the question "What is the nature of reality?"
There is no universal definition of Metaphysics, since it covers the most broad aspects of the universe, reality, and being. Metaphysics is traditionally subdivided in ontology, the theory of being in itself, and cosmology, the theory describing the origin and structure of the universe.
Aristotle aristotle divided Metaphysics into ontology, natural-theology, and universal-science.
