Yoga is an interior penetration leading to integration of being, senses, breath, mind, intelligence, consciousness, and Self. It is definitely an inward journey, evolution through involution, toward the Soul, which in turn desires to emerge and embrace you in its glory.
B.K.S. IyengarA scientist sets out to conquer nature through knowledge - external nature, external knowledge. By these means he may split the atom and achieve external power. A yogi sets out to explore his own internal nature, to penetrate the atom (atma) of being. He does not gain dominion over wide lands and restless seas, but over his own recalcitrant flesh and febrile mind.
B.K.S. IyengarPranayama teaches the aspirant to regulate his breathing and thereby control the mind.
B.K.S. Iyengar