The way we attain enlightenment is by purifying our very subtle mind of the two obstructions. We do this primarily through the meditation on the emptiness of our very subtle mind. The main purpose of tantric practice is to make manifest our very subtle mind of clear light of bliss in meditation. Once we do so, we then meditate on its emptiness.
The method for realizing the emptiness of anything is to identify how it normally appears to us, then differentiate its different parts, realize it is not the parts individually, the collection of the parts, or separate from the parts. How do we do that with the mind of the clear light of bliss, which is a similitude of a Buddha’s omniscient wisdom and Dharmakaya.
The way we realize its emptiness is by differentiating its parts like we do any other object, in this case the parts being the five omniscient wisdoms. In this case, the parts are mirror like wisdom appearing as clear light, the wisdom of equality manifesting as the feeling of great bliss, the wisdom of individual realization purely discriminating the five omniscient wisdoms as manifestations of their emptiness, the wisdom of accomplishing activities functioning as the purified mental factors holding the meditation on the emptiness of the clear light mind, and the wisdom of the Dharmadhatu cognizing purely the emptiness of the clear light mind. The function of the meditation on the emptiness of the very subtle mind is to completely purify our consciousness of the two obstructions.
An interesting question concerns what subsequently appears as the karmic effect of the mental action of meditating on the emptiness of the clear light mind.
Geshe-la said in Berlin when he was giving teachings on Sutra Mahamudra that the conventional mind is so clear it knows, and the more we realize its clarity the more we understand its power to know – essentially we realize clarity and cognizing are non-dual.
In the same way, it seems to me (but I am not sure since this is far beyond my personal experience) that when we realize the emptiness of the clear light mind and purify it of the two obstructions what appears is the Enjoyment Body and then subsequently the Emanation Body. It is like the clear light, while clear, is not realized at the stage of the union of bliss and emptiness as clear enough. But as we push through into the union that needs learning, we realize it is so clear it appears as the Enjoyment Body and later the Emanation Body. It is like we polish the clear light mind of the two obstructions until it starts to appear as the Enjoyment Body and Emanation Body, first with slight grasping at the duality between the clear light and the subsequent bodies during the union that needs learning until finally that duality is completely removed and we attain the Union of No More Learning.
Normally, we tend to think of the clear light mind as the basic construct of the Matrix – a vast space IN which we can then appear anything. That may work for generation stage, but in completion stage it seems to me the clear light mind is more like a mirror that when sufficiently polished appears AS the subsequent bodies. Just as the convention mind is so clear it knows, the very subtle mind of clear light is so clear it appears.
Geshe-la speaks of realizing the emptiness of the mandala that we normally see in generation stage. We visualize the mandala, but we start to grasp at it as inherently existent. We need to see past that to the union of appearance of the mandala as a manifestation of the emptiness of all phenomena – the union of appearance and emptiness. I believe we need to do the exact same thing with the clear light we normally see. Just as there is the mandala we normally see, so too there is the clear light we normally see. When we see past that, the clear light appears as the subsequent bodies.
The scriptural citation for this is the last paragraph of the Lord of All Lineages Prayer. “Through completing the practice of this clear light I will attain the actual Union of Great Keajra, the state of enlightenment. This is the great kindness of Guru Heruka; May I become just like you.” Completing the practice of clear light means purifying it of the two obstructions until it spontaneously appears as the totality of Great Keajra, which is the Dharmakaya so clear, so empty, it appears spontaneously as non-dual appearance and clarity of the mandala. The Union of Great Keajra is distinct from both the Keajra that we normally see and the clear light that we normally see. An additional citation is in NEOV when it says the third function of the meditation on non-dual appearance and emptiness is “Through meditating on the union of appearance and emptiness we will attain the Union of the state of No More Learning, Buddhahood, in this life.” Put another way, the meditations of the union that needs learning is the completion stage version of the generation stage meditation on non-dual appearance and emptiness.
In short, the clear light Dharmakaya is not our final end state, but the mirror like basis for the other bodies appearing. It is so clear, so empty, it appears.