His Holiness the 14th Dalai Lama once wrote that the Sacred Syllable OM (AUM) represents purity of body, speech, and mind. This is Buddhahood, or Buddha Consciousness, when one lives in a way that is pure mentally, physically, and verbally. There are hundreds of sacred and auspicious prayers in Tibetan Buddhism, for example, that begin with the Sacred Syllable OM. From the vantage point of Vedanta philosophy, all beings that manifest through these mantras are Divine Forms of OM. A case in point is Mother Tara (like Red Tara), and one of her mantras is OM TARE TAM SOHA. Notice that the mantra begins with OM. This Divine Buddha (in a female form as Mother Tara) is a compassionate sound-form of the Sacred Syllable OM. If you invoke the presence of the Adi-Buddha (the Original Buddha), you can pray/recite OM SAMANTHABADRA HUM. So, even the Adi Buddha is a sound emanation and form coming out of the Infinite Sacred Syllable OM.