When the mind is turbulent, uncontrolled and restless, it is like a pond of water that is filled with mud. Therefore when we look within ourselves, all we perceive is the mud of our material conceptions of life. But when the mind is still through discipline, and through yoga, it is like a pond that has no waves and no turbulence. Then we can perceive through that crystal clear water the eternal nature of our soul.
– Radhanath Swami