Tatah Parama Vasyatendriyanam (II/55)
= then (after Pratyahara); Parama = highest; Vasyat
= mastery; Endriyanam = over the senses.
From pratyahara, the greatest mastery over the senses
When we learn to use our senses properly through Pratyahara, we gain mastery over them. Senses are like instruments which should function at our will and not at their own. Imagine the chaos when the light in the room is put on or the fan starts functioning without switching the button on. Same thing happens to us when we become slaves to the senses. Pratyahara does not mean to run away from the world but to use the senses as master. The monks, the Sanyasins in India are addressed as Swami (the master). Because they have complete mastery over themselves. They are free to move anywhere and be happy everywhere and are fearless because they do not depend on any outwards source for their comfort or survival. Even the kings used to honour them in our country. Not only this, seeing the wonder of inner world that one achieves through mastery over the senses, great kings like Mahavir, Buddha and Ashoka renounced their kingdom. Bhagwan Mahavir, the founder of jainism, is also known as Jitendra (Jit-indriya i.e. one who has won his indriyas, the senses). That is why his followers are called Jains. Jain munis and their followers, by leading an austere life and mastery over senses, lead a serene life leading to utmost satisfaction.
Bahiranga Yoga, the first five steps of Ashtanga Yoga, leads to antaranga Yoga by removing various disturbances (emotional by Yama and Niyama, Physical disturbances (emotional by Yama and Niyama, physical disturbances by asanas, pranic disturbances by Pranayama and extrovert nature of mind through senses by Pratyahara.