The Incomprehensible Power of the mantras to change one's whole life, on all its levels from karma,mind and emotions to the physical level cannot be understood but only experienced.
Mantras - the name comes from the root Man=mind and Tra=protect. however mantras are much more than a way of "protecting" one from the wonderings of the mind. As is done when repeating a simple word or sound with the intention of reaching a state of concentration upon it.
The mantras are sounds and words of power that, when properly activated by initiation, resonate with specific forces in the universe, and can make these forces become alive in the practitioner.
The mantras are of two kinds, bija mantras and long mantras.
The bija (seed) mantras are single syllabic and each once of these corresponds to a specific kind of energy or shakti (power) which exists in the universe and therefore also in the human organism (according to the adage “what is found outside is found in the body & what is not found in the body will not be found outside” as expounded in the Shiva Samhita).
The long mantras are mantras composed by the combination of different bija's and words, giving rise to complex and unique forces which can be tailor suited for each occasion.
The mantras affect the human organism on all its levels; The Karmic-causal, Mental-Emotional, Energetic & Physical.
As the mantras themselves and the forces working behind them are coming from levels of existence which are beyond the mind (and will lead the aspirant beyond his) it is quite impossible to use words and concepts (which are of the mind) to explain the way in which these mantras work.
However their efficacy can easily be verified by practice, in a very short time powerful results are noticed.
The mantras are used ultimately in order to raise the kundalini energy from its seat in the base of the spine the muladhara chakra to the Apex of the Skull, the Sahasrara. In terms of kundalini yoga, when the kundalini has risen to sahasrara one achieves the state of samadhi.
How the mantras do this we cannot say as we ourselves do not comprehend it. Yet objectively all the signs both external and internal that one manifests in a kundalini rising are experienced.
While in the Kundalini mudras of hatha yoga, the kundalini is raised in a powerful way for a short time, giving rise to transient states of high consciousness. When using the Tantric Mantra Sadhana the kundalini's rise is slower. However any “state” achieved becomes a permanent shift in consciousness. And so while with the kundalini mudras one suffers a “fall” into mundane consciousness after one has stopped the practice, with the Tantric mantra sadhana the practitioner, step by step, raises his consciousness, until it will reach its peak. And never again fall down.