Matter is a foundational concept in metaphysics referring broadly to the physical or material aspect of reality. Metaphysical inquiry asks whether matter is the most basic substance of existence, whether it depends upon other principles such as form or mind, and how material things persist through change, causation, space, time, and identity. Questions about matter are closely connected with the Mind-Body Problem, materialism, dualism, substance, and theories concerning the relationship between physical reality and conscious experience.