The Vedantin studies the three states. He gains more real knowledge from deep sleep state. He gets a clue for the existence of the fourth state or the state of Turiya from the deep sleep state. The soul is beyond the realm of physical science. The soul is beyond the reach of material science.
Man is a soul, wearing the physical body.
The soul is extremely subtle. It is subtler than ether, mind and energy. Consciousness and intelligence are of the soul, and not of the body. Consciousness is evidence of the existence of the soul. The soul is the immortal part of man.