To reach enlightenment, we need to remove forever two sets of obscurations:emotional obscurations (nyon-sgrib) – those that are disturbing emotions and attitudes and which prevent liberation,
cognitive obscurations (shes-sgrib) -- those regarding all knowables and which prevent omniscience. These obscurations bring us, respectively, the suffering of uncontrollably recurring existence (samsara) and the inability to be of best help to others. They are fleeting (glo-bur), however, and merely obscure the essential nature (ngo-bo) of the mind and limit its functioning. In essence, the mind (mental activity) is naturally pure of all fleeting stains. This is an important aspect of its Buddha-nature.
Mental activity occurs on two levels, with limited awareness (sems) and pure awareness (rig-pa). Since many Western students are already familiar with the Tibetan terms, let us use them for ease of discussion. Sem is mental activity limited by fleeting stains. Rigpa is mental activity devoid of all fleeting stains of obscuration.
Sem may be conceptualor nonconceptual and, in either case, is always stained. Rigpa, on the other hand, is exclusively nonconceptual, in a purer manner than is nonconceptual sem, and is never stained by either of the two sets of obscurations.
Since mental activity, whether limited or pure, is naturally devoid of fleeting stains, rigpa is the natural state of sem. Thus, rigpa, with its essential nature of being devoid of all stains, can be recognized as the basis of each moment of our cognition. Dzogchen, then, is a method of practice, grounded in bodhichitta and nonconceptual cognition of voidness, enabling us to recognize rigpa and stay forever at its level of mental activity free from all obscuration. In this way, rigpa’s “great completeness” (dzogchen) of all enlightening qualities for benefiting others becomes fully operational.