The “OM” mantra is the composite sound of four major sounds: AA (like AH), UU (like OO), MM (like MM) and silence. Each sound, metaphysically, represents a plane of reality. The AA sound represents the gross, physical plane. The UU sound represents the astral or subtle physical plane. The MM sound represents the causal or mental plane. Finally, the silence that manifests after the OM chant represents The Absolute Plane Itself, which is beyond description. So, as you chant OM mindfully, and with great sincerity, you are recognizing the full span of existence between manifested planes as well as the Original Plane. As you chant OM, you are effectively saying “Dear God, I honor the physical plane and all beings in this plane, I honor the astral plane and all beings there, I honor the causal plane and all beings there, and I of course honor the Absolute Plane, which is You, Yourself”. Namaste.