This Vedic word "OM" is compose of three letters. A (अ) , U (ऊ) , & M (म). "A" corresponds to the waking condition of the Self, "U" corresponds to the dreaming condition of the Self, and "M" corresponds to the deep sleep state of the Self. Beyond all these condition lies the indivisible Self which is the witness of all these conditions. When perception is turned outward, this Self perceives the material universe, when perception in turned inward it experiences dreaming and deep sleep state. "A" merge into "U" and both merge into "M". Beyond "M" there is silence. This silence is the indivisible Self whose existence can only be felt by union with it. From OM comes all this manifestation, in OM dissolves all this manifestation. Past, present, and future are all OM and that which transcends all time is also OM. ओम शान्ति: शान्ति: शान्ति: l