Anything physical is always changing, therefore, its reality is not constant, not eternal.
B.K.S. IyengarHatha Yoga teaches us to use the body as the bow, asana as the arrow, and the soul the target.
B.K.S. IyengarMind is the king of the senses; breath is the king of the mind; and the nerves are king of the breath.
B.K.S. Iyengar