Mantras are the purest form of universal vibrations, or shakti, the profundity of which was experienced by the Rishis in deep meditation. Mantra is the power of the universe in seed form. That is why they are known as bijaksharas (seed letters). Having gone through that experience, they offered these pure sounds to humanity. However, verbally encapsulating an experience, particularly the most profound of all experiences, is not so easy. So, the mantras we have are the closest sounds to the universal sound that the compassionate Rishis could verbally create for the benefit of the world. However, the fact still remains that the fullness of a mantra can only be experienced when your. mind attains perfect purity.