Metaphysics is the science or philosophy which systematically investigates the nature of first causes or principles of all existence, ultimate reality, knowledge, being and the nature of the universe.
As a belief system metaphysicsIt covers a broad spectrum of ideas and concepts as well as providing a mental discipline. The old dictate of "know thyself" is apropos for a person practicing metaphysics.
Metaphysics is the way to interpret and understand life on the physical, mental, emotional and spiritual planes. The division of psychology dealing with metaphysical concepts is called parapsychology as it deals with things that go beyond the five senses.
Metaphysics is seen as a Science because our belief system is demonstrated and manifested in concrete terms, a philosophy since it helps us to understand life and for many it serves as a Religion because it teaches us our relationship with God(dess).