This thread is about Buddha Nature.
As can be seen, there are various positions regarding whether Buddha Nature is an expedient or an absolute. Whether it is pedagogical, or ontological. Whether it is reconcilable with Madhyamika and with Sunyata (emptiness).
But let's talk about emptiness. As has been said, all discussions about the absolute are by nature expedient. It is clear that the absolute--Dharmakaya, Buddhahood, the Dharmadhatu--is beyond the limits of language. Madhyamika, which is not a provisional truth, teaches that all conditioned phenomena have no existence. All phenomena are empty. But there is no such "thing" as emptiness. In fact, the emptiness of the phenomenon and the phenomenon itself are dependent on each other. There is no emptiness apart from phenomena. As the Heart Sutra says, "Form is emptiness; emptiness is form."
Until one reaches the First Bodhisattva level, at least, it's said one merely has a conceptual emptiness. Direct experience of emptiness occurs at very high levels, and, until very close to Buddhahood, only in meditation sessions--not during post-meditation. Emptiness is a non-affirming negation-- so, from a conventional POV (which is, as noted, all we can talk about), when we have an understanding of Emptiness, we view the integral "identity" of phenomena and their appearance as nondual. But this is a conceptual nonduality--we can say "emptiness primordially coemergent with appearance." From the POV of "views," this is a very powerful tool, as it lessens attachment at very early stages of understanding, and allows one to cut through elaboration as one progresses on the Paths. This tool is meant to be used, not as a device or stance for "winning arguments" per se, but as a tool for meditators. A means of practice. After all, even if one understands emptiness, one is still left with conventional appearances, dependent arising, the law of karma, and mundane cause and effect--one can say "it's not that," "There is no existence," etc., but the important thing is to train one's mind in nonattachment - to phenomena, which includes "external" objects, but also to "internal" concepts and thoughts themselves--during meditation, and to "view all existence as illusory" in post-meditation.
Now, Buddha Nature.........I'll be back to discuss.
"Absolute Truth is not an object of analytical discourse or great discriminating wisdom,
It is realized through the blessing grace of the Guru and fortunate Karmic potential.
Like this, mistaken ideas of discriminating wisdom are clarified."
- (Kyabje Bokar Rinpoche, from his summary of "The Ocean of Definitive Meaning")