Om Mani Padme Hum

Om mani padme hum is the most important mantra in buddhism.It is the six syllable mantra of the bodhisattva of the compassion Avalokiteshvra. The Dalai lama is said to be an incarnation of avalokiteshvara, so the mantra is especially revered by his devotees.

Om mani padme hum is "Om jewel in the lotus hum"or "Praise to the jewel in the lotus."However, the meaning and the significance of the six Tibetan syllables have been interpreted in a variety of ways.one common interpretation is that each syllable corresponds to one of the six realms of  existence and purifies the vice associated with that realm.
..Om purifies bliss and pride(realm of the gods)
..Ma purifies jealousy and need for entertainment(realm of jealous god)
..Ni purifies passion and desire(human realm)
..Pad purifies ignorance and prejudice(animal realm)
..Me purifies poverty and possessiveness(realm of the hungry ghost)
..Hum purifies aggression and hatred (hell realm).
It has also been said that recitation of each of the syllables prevents rebirth in the corrosponding realm.
The first known description of the mantra apprears in the karandavyuha sutra, which is part of certain Mahayana canons such as the Tibetan canon.In This sutyra,the Buddha says:
"Thius is the mist beneficial mantra. Even i made this aspiration to all the million Buddhas and subsequently received this teaching from Buddha Amitabha."
In the book Heat Treasure of the Enlightened Ones,Gen Rinpoche says of the mantra:
"The mantra Om Mani Padme Hum is easy to say yet quite powerful,because it contains the essence of the entire Teachings When you say first syllable Om is blessed to help you achieve perfection in the practice of generiousity., Ma helps perfect the practice of pure ethics,and Ni helps achieve perfection in the practice of tolerance and patience.Pad  helps to achieve perfection of perseverance, Me helps achieve perfection in the practice of concentration,and the final Hum helps achieve perfection in the practice of wisdom.
So in this way recitation of the mantra helps achieve perfection in the six practice from generousity to wisdom.the path of there six perfection is the path walked bt all the buddhas of the three times.What could then be more meaningful than to say the mantra and accomplish the six perfections.