The sacred symbol Om (Aum), which in Hindu philosophy is said to represent the primordial sound of the universe, is widely used in mainstream Buddhism, though it has differing connotations.
It is a little known fact that Gautama Buddha discouraged the use of mantras and other “magical” terms as practiced in the Vedas. Later however, the Mahayana and Vajrayana schools of Buddhism adopted Vedic traditions like chanting mantras and meditation as a way of self-protection and spiritual purification.
To Buddhists, Om represents the external aspects of a sentient being – his body, speech and mind. The best known use of the mantra is in the Tibetan Buddhist prayer Om Mani Padme Hum, also known as the Mani mantra. When chanted loudly or silently within, the mantra invokes Chenrezig, the Buddha of Compassion. Even looking at a written version of the mantra produces the effect of attracting the blessings of Chenrezig. For this reason, the mantra is carved into prominently displayed stones, where it can easily be spotted. In this mantra, chanting “Om” loosens the grip of the ego on the mind. His Holiness The Dalai Lama, expounding on the power of the Mani mantra, once said that by chanting it regularly, “you can transform your impure body, speech and mind into the pure body, speech, and mind of a Buddha.”