This view on the cosmos’ emptiness, the primordial nothingness, could not have been Nāgārjuna’s reference to past wisdom.
He may have delved in Buddha’s teachings and come across the Sutta on emptiness and its later 2.0-version the extended Sutta on emptiness. Just as the equally Small Vehicle Phena Sutta (SN 22.95): the Teaching on froth (or foam), the two above texts are about the absence of ens in living beings, and in the Phena Sutta it’s about even the absence of essence in material things such as froth on water. This Phena Sutta then could have been Buddha’s first mention of emptiness (sunyā) beyond the mere mortal.
The Phena Sutta: “ … Monks, suppose that a large glob of froth were floating down this Ganges River, and a man with good eyesight were to see it, observe it, and thoroughly examine it. To him … it would appear empty, without substance: for what substance would there be in a glob of froth?
Nevertheless Nāgārjuna may not have been entirely satisfied with this too. For him, it didn’t do. He wished to go a step further in order to deal with the entire Chain of Dependent Arising, including the functioning, the process of Dependent Arising itself. In doing so he amplified the teaching on emptiness beyond the initial goal of bringing the individual to examine himself to see and witness that all within his own frame is fleeting, that nothing in it can be grasped and that therefore there is no need to be overly concerned with your individual life since it is empty of substance and ultimately cannot be governed – “I cannot say: let me look like this, let me be like that”, a paraphrase of one of the early teachings.
In his Teachings on the Roots of the Middle Way (Mūla-madhyámaka-kārika – Ch.24,18) Nāgārjuna writes the word sūnya in the genetive: sūyatam: the Dependent Arising’s emptiness. This is important for a correct understanding of the stanza:
“Yah pratītyasamutpāda sūnyatām tām pracaksmahe /
sā prajñaptir upādāya pratipat saiva (sa-iva) madhyamā.”
I STATE THE DEPENDENT ARISING’S EMPTINESS /
I PERCEIVE THE DEPENDENT ARISING’S EMPTINESS AS CONTIGENT ON (UPĀDĀYA) /
CONVENTION. THAT (the dependent arising’s emptiness) IS THE MIDDLE (way or path).
I.e. first with our ordinary mind we perceive how phenomena come to be dependent upon one another, e.g. a flower as result of the presence of soil, water, air, and light. After a while with our well trained mind we realize that both the phenomena and the arising as a process are empty of content or own-being. This own-being in Buddhist parlance is svabhāva.
This is the thorough emptiness that Nāgārjuna postulated, going beyond the earlier realisation of emptiness as (merely) a living being devoid of ever-abiding, never-changing self. Nāgārjuna says that both the object and the process of perceiving the object are empty (sunyā). In doing so he, and not Vasubandhu whose words will be discussed below is the true father or inventor of the thoroughly Mahāyānistic “Consciousness-only school” otherwise known as the Yogacára.