 The mantra OM should therefore lead towards the opening of the consciousness to the sight and feeling of the One Consciousness in all material things, in the inner being and in the supraphysical worlds, in the causal plane above now superconscient to us and, finally, the supreme liberated transcendence above all cosmic existence.The last is usually the main preoccupation with those who use the mantra.” "Letters on Yoga", Vol.II, p. 745-46

“If you are a serious student of Vedic mantras, you will chant Om because Vedic mantras begin with Om.