For Tāra day, am happy to publish the first translation of a small teaching given in response to a question by the 8th Karmapa, Mikyo Dorje, on Buddha-Nature and Dharmakāya from Volume 3 of his Collected Works (that contains several short teachings in answer to questions):
”In response to your question: Even though the resultant Tathāgata (Buddha Nature) and the Dharmakāya have the same nature, the causal Tathāgata is not the Dharmakāya. It is the ultimate completion of the two accumulations [merit and wisdom] and purification of the two obscurations. It is devoid of the five aggregates, twelve sense spheres and eighteen elements. It is the eight consciousness heaps that transform into the three kāyas, five primordial wisdoms, enlightened activities and so on. The meaning of that assembly is affixed the label dharmakāya.
Therefore, in the resultant Tathāgata, there are the two: ultimate svabhāvikakāya and the relative form kāya. First, the cause of the svabhāvikakāya (Nature-Truth Body). Primordially present in the mindstreams of all sentient beings, whose nature is completely pure and in which the obscurations do not essentially abide. Its name is:
‘naturally abiding affinity, continually present Tathāgata . In the secret mantra texts, it bears the name ‘the Buddha function’ and the ‘vajra-base function’ and so on.
Second, is the cause of the form kāya. In dependence on love, confidence and the ten virtues in the mind -streams of all sentient beings and other conditions, the Buddhas arrive in the world and so on. The habitual tendency of listening rises up, waking up the habitual tendency for virtue. This is also existent at the time of the cause of Buddha Nature and distinguished by the name ‘six sense bases’. The activity of the habitual tendency of listening and so on has several names. However, in the natural emptiness of mind, when the various deluded interdependent appearances bound to the two obscurations arise, that is saṃsāra. When the empty nature of mind due to the various interdependence of purification and accumulation that liberates without delusion from the two obscurations, that is the non-abiding nirvāṇa. However, since in the truly existent nirvāṇa the delusion of saṃsāra is a delusion and saṃsāra does not truly exist and is false, It does not enter into the way of abiding in an object/place.
As for nirvāṇa, since it is unmistaken and undeluded it is posited as the ultimate truth. Like that, false saṃsāra and ultimate truth are posited. There are those who assert an ‘ultimate expressible with words’, and an ‘ultimate not expressible with words’. In our own glorious tradition, when positing the conventional truth, ultimate and temporary are not both existent. During the ‘temporary’ state, the ultimate itself is truly existent yet at that time an illustration (basis of characteristics) of the truth of nirvana alone is posited. Even though it is taught like that, nirvāṇa [gone beyond suffering] also is not the ultimate nature itself. Since it has not gone beyond ‘conditioning’ (‘dus byas). Therefore, in secret mantra texts, it [the ultimate] is explained as the final ‘non-dual bliss-emptiness mahāmudra’. That ‘non-dual bliss-emptiness’, on the vajrayana path of the Noble Arya mindstream onwards, the objectless love, bliss of conventional bodhicitta, that is one taste with the empty mind of ultimate bodhi mind free of elaborations, is the meaning of the function of the ‘indivisible union of bliss-emptiness’. This was said at Yung Jadrel. Thus it is said. Shubham”
Translated and edited by Adele Tomlin, 24th September 2020. Copyright.
 “bde gshegs snying po dang chos sku’i dris lan/.” In gsung ‘bum/_mi bskyod rdo rje. TBRC W8039. 3: 323 – 326. Lhasa edition .
 The two obscurations are 1) afflictive obscurations (kleśa-avaraṇa, nyon-mongs-pa’i sgrib-ma) which are defined according to their essence, cause and function. In essence, they are the opposite of the six paramitas. Their cause is grasping at a personal ego, or the “self of the individual”. They function to prevent liberation from samsara. 2) Cognitive obscurations (jñeya-avaraṇa, shes-bya’i sgrib-ma) are defined according to their essence, cause and function. In essence, they are thoughts that involve the three conceptual ‘spheres’ of subject, object and action. Their cause is grasping at phenomena as truly existent, or, in other words, the “self of phenomena”. Their function is to prevent complete enlightenment.
 The twelve sense fields (skye mchad bcu gnyis) are: the six inner (eye, ear, etc.) and the six outer (form, sound, etc.). In general, these are equivalent to the eighteen elements (khams or dhatu), in which the sense base of mind is divided into six consciousnesses and the element of mind. In the context of the sense bases, the emphasis is more on the constituents which produced the present consciousness; in terms of the elements the emphasis is on the constituents that will produce the future consciousness.
 kun rdzob gzugs kyi sku.
 rang bzhin du gnas pa’i rigs rgyud dus kyi bder gshegs snying po.
 sangs rgyas bya ba dang/ gzhi kyi rdo rje bya ba/.
 The six sense bases (āyatana), that is, the sense organs and their objects. These are: Eye and Vision, Ear and Hearing, Nose and Smell, Tongue and Taste, Skin and Touch, Mind and Thought.
 Ultimate reality that can be expressed in words, from the Yogacara- svatantrikas.