The mantras of all Buddhas. Mantra literally means ‘mind protection’. By reciting mantras with strong faith and concentration we protect our mind from ordinary views and thoughts. There are many different mantras, but they are all contained within these three letters. OM is the mantra of the bodies of all Buddhas, AH is the mantra of the speech of all Buddhas, and HUM is the mantra of the minds of all Buddhas. If we recite these three letters with faith we receive the blessings of the body, speech and mind of all Buddhas.