Sound is the key word of Mantra Yoga. Sound is the primordial form of energy, the original substance and basis of whole universe. This universe with its solar systems, its invisible fields of energy, is an expansion of sound energy. This sound is known as ‘shabda’ in Yoga, ‘the word’ in the Bible, and ‘mantra’ in the Tantric System. Sound has different stages of manifestations. Every type of energy from the primordial to the manifest state undergoes transformations, changes frequency, velocity, etc. when we talk about mantra, we are definitely talking about one of the manifestations of this primordial energy. Each letter and syllable of the mantra penetrates deep down into various levels of our consciousness.