The subtlest level of mental activity, called clear light (‘od-gsal) in the non-Nyingma systems, may be presented as either

• The actual nature of things (chos-nyid), referring to voidness, or

• Something that has this actual nature (chos-can), namely a way of being aware of things.

The former is clear light as an object of cognition (yul), and the latter is clear light as something that takes an object (yul-can). Often, the former is called object clear light and the latter cognitive (subject) clear light.

Cognitive clear light naturally has voidness (object clear light) as its deepest nature. Ultimately, then, to remove forever all suffering and its causes, we wish to achieve a cognitive clear light that cognizes its own nature – object clear light – as its cognitive object.

There are several approaches to gaining the realization of combined cognitive and object clear light. The differences are prominent in the style of voidness meditation practiced on the generation stage ( bskyed-rim) of anuttarayoga tantra – or of mahayoga tantra in the Nyingma system – when we merely imagine accessing the clear light level (or rigpa, pure awareness, in dzogchen), but are unable to do so yet.

Self-Voidness and Other-Voidness

Within the context of gaining a clear light realization that is both a cognitive and object clear light, voidness may be either self-voidness (rang-stong), other-voidness (gzhan-stong), or both.

Self-voidness is the total absence of impossible ways of existing. The impossible ways may be:

• With truly established existence (bden-par grub-pa, true existence), or

• With existence that corresponds to the words or concepts (1) truly established existence, (2) non-truly established existence, (3) both truly established existence and non-truly established existence, or (4) neither truly established existence nor non-truly established existence.

According to the non-Gelug schools, self-voidness of the first type of impossible way of existing is a denumerable ultimate phenomenon (rnam-grangs­-pa’i don-dam), and can only be known conceptually. Self-voidness of the second type of impossible way of existing is a non-denumerable ultimate phenomenon (rnam-grangs ma-yin-pa’i don-dam), and can only be known non-conceptually. This is voidness that is beyond words and concepts.

Gelug asserts that self-voidness (although it calls it simply “voidness”) is exclusively a voidness of truly established existence. Truly established existence includes truly established (1) true existence, (2) non-true existence, (3) both, and (4) neither. When such a voidness is cognized conceptually, it is a denumerable ultimate phenomenon. When it is cognized non-conceptually, it is a non-denumerable voidness.

Other-voidness, asserted by some of the non-Gelug traditions, is clear light mental activity being totally devoid of rougher levels of mental activity, including all conceptual cognition and fleeting stains. It too is a voidness beyond words and concepts.

[See: Ultimate Phenomena: Denumerable and Non-denumerable]

Approaches to Self-Voidness Meditation

1. In Gelug mother tantra, such as Chakrasamvara, we meditate first on voidness as the total absence of true existence. We then imagine dissolving the energy-winds so that the mental activity cognizing voidness becomes increasingly subtler until it is clear light cognition of voidness.

2. In Gelug father tantra, such as Guhyasamaja, we first imagine dissolving the energy-winds until we reach clear light mental activity. We then recall and apply as the object of cognition of this clear light mind our previous understanding of voidness as the total absence of true existence.

3. In Sakya anuttarayoga tantra, such as Hevajra, we meditate first on the voidness of cognitive appearances as items existing separately from being the play of the mind, in the Chittamatra sense. Then, we meditate on the voidness of their existing separately from what arises dependently on karma, also in the Chittamatra sense. Next, we meditate on the denumerable voidness of the true existence of cognitive appearances and of the mind of which they are the karmic play. We then meditate on the non-denumerable voidness of both – their existing beyond words and concepts – and thus imagine reaching the clear light level. Implicit is that we dissolve the energy-winds to reach that level, but we imagine that happening only with the final dissolution at the end of the sadhana practice.

4. In some Kagyu anuttarayoga tantra practices, we meditate first on the non-denumerable voidness of cognitive appearances and the cognitions giving rise to them. Non-denumerable voidness, here, is formulated in terms of an absence of dualistic existence. We may do this in one step, as in Karma Kagyu Vajrayogini, or in two steps, one for cognitive appearances and one for cognitions, as in Shangpa Kagyu Chakrasamvara. Then, as in Sakya, we imagine reaching the clear light level, but we do not actually imagine the dissolution of the energy-winds to reach that level until the end of the practice.

All these methods share in common direct meditation on self-voidness. None of them, however, entails analysis or analytical meditation. We merely recall our understandings of self-voidness from analytical meditation done in previous meditation.

Approaches to Other-Voidness Meditation

1. In some Kagyu practices, such as the above-mentioned Shangpa Kagyu Chakrasamvara, we meditate on the clear light level being totally devoid of the levels of mind that make dual appearances (of separately existent cognitive appearances and of separately existent cognitions, corresponding to what the words and concepts for them conceptually imply). Then, as above, we imagine reaching the clear light level, but we do not actually imagine the dissolution of the energy-winds to reach that level until the end of the practice.

2. In Nyingma dzogchen practices, such as Hayagriva, we meditate on the characteristics of rigpa and imagine instantly activating that level of mental activity. We do not imagine, either here or elsewhere in the practice, dissolving the energy-winds in stages to reach rigpa.

These methods share in common direct meditation on other-voidness and indirect meditation on self-voidness. After absorption on other-voidness clear light or rigpa, we focus on all appearances being the play of the other-voidness subtlest mind. Indirectly from this, we understand that subtlest mental activity lacks truly established existence, as defined in Gelug-Prasangika. This is because since clear light or rigpa has appearances as its play, it functions. If it functions, it cannot be truly existent – there cannot be anything findable on the side of clear light that, by its own power, establishes its existence.