mano ’cirat syad virajam

 jita-svasasya yoginah

vayv-agnibhyam yatha loham

 dhmatam tyajati vai malam

 

Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 

 

The yogis who practice such breathing exercises are very soon freed from all mental disturbances, just as gold, when put into fire and fanned with air, becomes free from all impurities.

 

Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 

 

This process of purifying the mind is also recommended by Lord Caitanya; He says that one should chant Hare Krsna. He says further, param vijayate: “All glories to Sri Krsna sankirtana!” All glories are given to the chanting of the holy names of Krsna because as soon as one begins this process of chanting, the mind becomes purified. Ceto-darpana-marjanam: by chanting the holy name of Krsna one is cleansed of the dirt that accumulates in the mind. One can purify the mind either by the breathing process or by the chanting process, just as one can purify gold by putting it in a fire and fanning it with a bellows.