In his Treatise on the Maha-Prajna-Paramita Sutra, Nagarjuna writes,
Emptiness demolishes all dharmas (concepts) so that the only thing that abides is emptiness (sunyata). After emptiness has already demolished all dharmas, emptiness itself should also be set aside. It is because of this that we require the ‘emptiness of emptiness’ (sunyata-sunyata). Whereas emptiness conditions all dharmas, the emptiness of emptiness conditions only emptiness.”
This explains once again why emptiness is not the ultimate truth. We can say the same about nonduality. Some folks find this confusing, especially when we say that from the Madhyamaka or Middle Way point of view ‘neither-emptiness-nor-non-emptiness’ and ‘neither-duality-nor-non-duality’ is the ultimate truth. These two phrases represent a middle path, as close as we can come to expressing the ultimate, as it is ultimately ineffable. Although Nagarjuna equated the ultimate with the Middle Way, he taught that actually “The ultimate truth is not any view. Silence is the ultimate truth for the wise.”
In his book Essence of the Heart Sutra, the Dalai Lama explains what Nagarjuna means when he says that emptiness conditions dharmas:
For example, when we speak of the emptiness of a form, we are talking about the ultimate reality of that form, the fact that it is devoid of intrinsic existence. That emptiness is the ultimate nature of that form. Emptiness exists only a quality of a particular phenomena; emptiness does not exist separately and independently of particular phenomena.”
In the passage from his Treatise, Nagarjuna also compares emptiness to medicine – the “antidote” to the disease that comes from delusions originating from the attachments to self-being and dharmas. However, once the disease has been cured, there is no further need for the medicine. Again, why we require the ‘emptiness of emptiness’.
Nagarjuna cautions us about clinging to the idea of emptiness, for when emptiness is seized there is always the temptation to misuse it, to fling it about as another view. Emptiness does not ‘exist’ for its own sake as a concept or a kind of dogma; all things are empty, even emptiness. And so, emptiness is a tool that must be employed skillfully, and Nagarjuna warns,
Emptiness wrongly grasped is like picking up a poisonous snake by the wrong end.”
Nothing terribly bad will happen if we misunderstand or misuse emptiness, no punishments will befall us, but it does tend to push us further from the liberation from suffering, the peace and joy, we seek.