In Mantra Yoga a person comes in touch with the mysticism of sound when he begins to see and understand; he begins to see that he gains power by sound, that in every vowel, word, composition, a certain effect or element is hidden, because life and the whole of manifestation is the outcome of what may be called vibrations. The scientist today says that life is motion, but the mystic has said so for thousands of years. At the same time he has worked with what the Hindus call Nada Brahma: sound-God or vibration-God. He has worked with life according to the law of vibrations, and has seen what great power vibration has. The whole of Mantra Yoga is based on this law of sound or vibrations. But this is a very big subject.