The person who sits is more ready to bring forth clear things than someone who walks or stands. Sitting means peace. Thus we sit, which is bowing in humility among all creatures. Then the individual comes to a quiet peace reaching this peace in light. The light is given in the silence wherein one sits and dwells.
Breathing is the connection between the mind and the body. When the mind concentrates on the breath, it focuses attention on the present moment. Breathing is the first step on the path to discover your spiritual nature. As you get the body to breathe correctly, the mind settles down, and that creates fertile ground to develop whatever spiritual nature exists within you.