Now, actually, people are surprised: “What this Hare Krsna mantra has got power that it is changing so quickly?” And on the other hand, it is to be admitted, unless it has got power, how it is changing? So we have to keep that power. Don’t make it an ordinary musical vibration. It is a different thing — spiritual. Although it seems like musical vibration, but it is spiritual, completely. Mantrausadhi-vasa. Even, by mantra, the snakes can be charmed. So mantra is not ordinary sound vibration. So we have to keep the mantra in potency, potent, by offenseless chanting, by remaining pure. If you pollute the mantra, then it will lose its effect.

Srila Prabhupada — April 27, 1976, Auckland, New Zealand