"Body is an external self. Mind is an internal self. The real self is invisible. As the water is stored in a vessel, so this self is stored in a vessel, the body. So unless... Until the body is cleansed, purified, sanctified, how can you enter the gates of the soul? The body is like a fort, it's called purusha. Pura means a fort, so you have to enter the seven gates one after the other, from the skin, to the flesh, from the flesh to the mind, mind to intelligence, intelligence to the consciousness, consciousness to highness, highness to the conscience, conscience to the self. So there are so many gates in this fort. So unless you open the front gate, how can you enter the second gate or the third gate? That's the value of yoga. Yoga makes us to open the first gate so that the air may enter in, the cosmic force may enter in, and through that cosmic force, the other gates are entered, so that the external so-called body is one united with the internal self, the capital line which you don't change at all." BKS Iyengar
