Metaphysics is a traditional branch of philosophy concerned with explaining the fundamental nature of being and the world that encompasses it, although the term is not easily defined. Traditionally, metaphysics attempts to answer two basic questions in the broadest possible terms: Ultimately, what is there? What is it like? A person who studies metaphysics is called a metaphysicist or a metaphysician. The metaphysicist attempts to clarify the fundamental notions by which people understand the world, e.g., existence, objects and their properties, space and time, cause and effect, and possibility. A central branch of metaphysics is ontology, the investigation into the basic categories of being and how they relate to each other. Another central branch of metaphysics is cosmology, the study of the origin, fundamental structure, nature, and dynamics of the universe. This book discusses the branch of philosophy called metaphysics.