Hi Positron,
This mantra is the mantra of Chenrezig/Guan Yin. I'd post up a
article by His Holiness Penor Rinpoche on this mantra
later. It purifies your bad karma, creates good energy in
you, removes the obscurations that block your buddha-nature so that
you can realise emptiness, it creates merit and great blessings....
many people pray to Guan Yin for help in urgent situations like
accidents, disasters, great pain, sickness etc. And this
mantra is the main essential mantra of Guan Yin. Very very
powerful for healing, and wishfulfilling definitely. At the
end of your life, you will not fall into the lower realms and if
you are diligent, Guan Yin will guide you to Amitabha pureland.
Many Buddhists chant this mantra, because it is both short and
simple and yet full of blessings... there are many stories of
people who received spiritual accomplishments from a full faith and
practice of this mantra.
Make a target to chant at least 700,000 in your life. The
mantra blessings get stronger as you chant more...
700,000!!!That's alot.