[Sanskrit]

om

the mantra or expressive sound symbol of the brahman in its four domains from the turiya to the external or material plane (i e. the outward looking, the inward or subtle, and the superconscient causal - each letter A, U, M indicating one of these three in ascending order and the whole bringing out the fourth state, turiya); used as an initiating syllable pronounced as a benedictory prelude and sanction.