I think Bohiruci used to say recently that he would very much like to look into the teachings of Buddha Nature or Tathagathagarbha and has yet to learn more about it.
I was going through the pages at
http://www.empty-universe.com/, reading something on Anapanasati (mindfulness of breathing) and Vipassana, and then realised how huge a resource website it is.. it contains lots of valuable Buddhist resources from all sections -- from Theravada to Prajnaparamita to Yogacara to Tathagathagarbha to Vajrayana Sadhana.
And I think I just found something valuable for Bohiruci and all readers regarding the topic on Buddha Nature and I think the commentary by Thrangu Rinpoche is well written. It is the Mahayana Uttaratantra Shastra, spoken by Maitreya Bodhisattva.
Please read:
Buddha-nature with commentary by Thrangu RinpocheExcerpts:
What is Buddha Nature?27. The buddha essence is always present in everyone
because the dharmakaya of perfect Buddhahood pervades
everything,
this suchness is undifferentiated and they have the potential.
28. It is said that all beings possess the essence of Buddhahood
since the buddha jnana has always been present in them,
also because the immaculate nature is non-dual
and the buddha potential is named after its fruition.
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40. If there were no Buddha-nature
there would be no discontent with suffering
nor desire, effort, and aspiration for nirvana.-
41. Perception of suffering, samsaraÂ’s fault,
and happiness, nirvanaÂ’s quality, is due to the potentialÂ’s
presence.
Why should this be?
Without such potential it will not be present.
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49. Just as space, concept free by nature is all-embracing
so also is the immaculate space,
then nature of mind, all-pervading.
50. This, the general characteristic of all,
permeates the good, the bad, and the ultimate,
like space permeates all forms
whether lesser, mediocre, or perfect.
51. Since the faults are but accidental,
whereas its qualities are part of its very character,
it is the changeless reality, the same after as it was before.
52. Just as space pervades all but remains absolutely
unaffected; because of its extreme subtlety, similarly this,
present in all beings, remains absolutely taint-free.
53. Just as universes always arise
and disintegrate in space,
so also do the sense arise
and disintegrate in the uncreated space.
54. Just as space has never been consumed by fire,
likewise this is never consumed
by death, sickness, and ageingÂ’s fires.
55. Earth is supported by water, water by air, air by space.
But space is supported neither by air, water, nor earth.
56. In a similar way the aggregates, the elements, and the senses
are based upon karma and defilements.
Karma and the defilements are always based
upon the mode of thought which is wrong.
57. This improper mode of thought has
its basis in the mindÂ’s purity
whereas the true nature of mind
has no basis in any of the many phenomena.
58. The aggregates, entrances, and elements
should be known as being similar to earth.
The karma and defilements of beings
are to be known as similar to water.
59. The improper mode of thought is similar to air
whereas the true nature is like the element of space—
it has no base and no abiding.
60. The improper mode of thought abides
within the true nature of mind.
This improper mode of thought gives rise
to karma and the defilements.
61. From karma and defilementsÂ’ waters arise the aggregates, entrances, and elements,
arising and disintegrating just as
everything begins and has an end.
62. The nature of mind is like the element of space;
it has neither causes, nor conditions, nor these in
combination,
nor any arising, destruction, or abiding.
63. This true nature of mind—clarity—is like space,
unchanging, not becoming defiled by desire and so on,
passing impurities which from improper thinking spring.
64. It is not produced by the waters
of karma, defilements, and so forth
nor will it be burnt by the cruel fires
of ageing, sickness and death.
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79. Because it has inexhaustible qualities,
its nature is not to alter.
It is the refuge of beings
because it has no limits in the future, right to the very end.
It is always non-dual
because it is non-conceptual.
It is also of indestructible character
because, by nature, it is uncreated.
80. This has no birth because it is permanent,
no death because it is eternal,
no harm because it is peace, and
no aging because it is unchanging.
81. It has no birth in a mental form
because it is permanent.
It has not death
through inconceivable death and transmigration,
because it is eternal.
82. It is unharmed by the disease
of the finer karmic imprint because is peace.
It has no aging produced by untainted karma
because it is immutable.
83. This uncreated space has the attributes
of permanence and so forth
which should be known respectively through the first pair of
verses
and likewise the next pair and the next pair to the last.
84.6 “Being endowed with inexhaustible qualities
it has the attribute of permanence, the quality of not altering.
Because it equals the furthest end
its attribute is eternal, the nature of a refuge.
Because its very character is not to conceptualize,
it has the attribute of peace, the non-dual true nature.
As its qualities are not things fabricated,
its attribute is immutability, the changeless nature.
It is the dharmakaya. It is the tathagata.
It is the highest truth. It is the ultimately-true nirvana.
Like the sun and its rays, these aspects are inseparable;
so there is no nirvana apart from Buddhahood itself.
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158. The ultimate true nature is always
devoid of anything compounded:
so it is said that defilements, karma,
and their full ripening are like a cloud, etc.
159. The defilements are said to be like clouds,
karma is likened to the experience in dreams
and the full ripening of karma and the defilements—
the aggregates—are likened to conjurations.
(The above are related to the second turning)
160. Previously was it thus presented,
then, further to this, the presence of Buddha-nature
was taught ultimately in the “changeless continuity” as
here,9
so that these five faults could be abandoned.
(This is the third turning)