Raja Yoga is designed for persons of an experimental nature. The experiment being conducted is upon oneself; the hypothesis: that the human self is composed of three bodies, the Physical body, the Astral body, and the Causal body. In order to verify this hypothesis, and experience the subtle components of oneself, the raja yogi follows a system of concentration and mental control known as the Eightfold Path. Most of the popular styles of Yoga are forms or derivations of Raja Yoga (eg: Hatha, Vinyasa, Ashtanga, Kundalini).