Om/Ohm symbol is one of the oldest and most sacred symbols, It is a sacred syllable representing Brahman, the Absolute — omnipotent, omnipresent, and the source of all manifest existence. Brahman, in itself, is incomprehensible; so a symbol becomes mandatory to help us realize the Unknowable. Om, therefore, represents both the unmanifest (nirguna) and manifest (saguna) aspects of God. That is why it is called Pranava, to mean that it pervades life and runs through our prana or breath.