"Om Mani Padme Hum" (the Jewel in the Lotus) is the universal mantra of great love and great compassion. This mantra opens the mind to love and compassion and leads it towards awakening.

Each symbol has a purifying effect:
OM purifies the veils of the body.
MA purifies the veils of speech.
NI purifies the veils of mind.
PAD purifies the veils of conflicting emotions.
ME purifies the veils of latent conditioning.
HUM purifies the veil that covers knowledge.