Traditionally, metaphysics refers to the branch of philosophy that attempts to understand the fundamental nature of all reality, whether visible or invisible. It seeks a description so basic, so essentially simple, so all – inclusive that it applies to everything, whether divine or human or anything else.
To call one a metaphysician in this traditional, philosophical sense indicates nothing more than his or her interest in attempting to discover what underlies everything. Old materialists, who said that there is nothing but matter in motion, and current naturalists, who say that everything is made of lifeless, non – experiencing energy, are just as much to be classified as metaphysicians as are idealists, who maintain that there is nothing but ideas, or mind, or spirit.
A commonly employed, secondary, popular, usage of metaphysics includes a wide range of controversial phenomena believed by many people to exist beyond the physical, e.g. mysticism, referring to experiences of unity with the ultimate, commonly interpreted as the God who is love, and occultism, referring to the extension of knowing (extrasensory perception, including telepathy, clairvoyance, precognition, retrocognition, and mediumship) and doing (psychokinesis) beyond the usually recognized fields of human activity. The academic study of the occult (literally hidden) has been known as psychical research and, more recently, parapsychology.