Feeding The Fire

In many languages the words for spirit and breath are the same. In Sanskrit it’s prana, in Latin, spiritus, and in Hebrew, ruach. In Portuguese the word for taking in breath is inspiration, or spirit-in. They believe that an infant literally breathes its spirit into its body with its first breath. We breathe in life. Breath is the source of life and vitality. It is the spirit moving in rhythm in the body.
When the breath wanders, the mind is unsteady, but when the breath is still, so is the mind still.
Hatha Yoga Pradipika.

The Victorious Breath • Ujjayi Breathing
Breath is the fuel that feeds the internal fire, gives it life, keeps the flame going. The vital life energy, prana, is controlled by the breath. In vinyasa yoga, ujjayi breathing (victorious breath) is used to enrich prana. By breathing through the nose, with the mouth closed, the breath is felt from the throat, producing a hissing sound. This sound of the breath keeps the mind focused. As the mind begins to wander, the sound of the breath keeps bringing you back home and away from the mumbling, bumbling mind. The mind becomes focused and calm as each pose flows into the next in concert with the breath. The breath is the link between body and mind.”

-Ashtanga Yoga by Larry Schultz