In light of these investigations, Glasenapp summarizes the Buddhist path to liberation thus: liberation requires three trainings—śīla (ethical restraint, that is, right conduct), samādhi (concentration, that is, steadying the mind), and paññā (wisdom, that is, insight into the true nature of existence). The substance of this wisdom comprises three truths: all conditioned things are impermanent, all conditioned things are suffering, and all dharmas are selfless. Once these three insights are attained, the practitioner achieves, in this very lifetime, nirvana with substrate remaining—that is, craving and ignorance are extinguished, yet the body persists, and the old fruits of action continue to be experienced. After death comes nirvana without substrate remaining—that is, complete extinction, no conditioned existence whatsoever remains.
Finally, Glasenapp utters the culminating words of his entire analysis: nirvana too is a dharma—and all dharmas are without self. In other words, nirvana too is not a self. This is the cardinal idea of Buddhist philosophy: all dharmas—whether conditioned or unconditioned, whether saṃsāra or nirvana—are void of self. In this single sentence lies the distilled essence of Glasenapp's entire thought.
Vedānta's Neti Neti and the Five Sheaths: In Light of Negating Theology
The deepest epistemological method of Vedānta is neti neti—'not this, not this' (Bṛhadāraṇyaka 2.3.6; 4.5.15). This method must be grasped, for it brings Vedānta closest to Buddhist emptiness—and yet reveals the subtlest distinction between the two.
In the Bṛhadāraṇyaka Upaniṣad, Yājñavalkya is asked: what is Brahman? In his answer, he does not say what Brahman is—rather, he says what Brahman is not: 'not gross, not subtle; not short, not long; not red, not oily; shadowless, without darkness; without air, without space.' Each positive attribute is negated one by one—as if peeling the layers of an onion, stratum upon stratum. Vedānta's claim: even after all layers are peeled away, something remains—that is Brahman. Buddhism's claim would be otherwise: strip away all the layers and you will see there is nothing within—the onion is nothing but layers, there is no 'essence' at all.
This negating method—termed in Western theology apophatic theology or via negativa (the negative way)—has resonated through various spiritual traditions across the world. The Greco-Roman Neoplatonist Plotinus (205-270 CE), in his Enneads, speaks of the ultimate reality, 'The One' (to hen), as transcending all attributes—'beyond being' (epekeina tes ousias). Just as the eye becomes blind when looking directly at the sun—the light so intense that nothing is seen—so too the ultimate unity cannot be grasped by intellect, but only through 'henosis' (union)—that is, losing oneself in that unity—it becomes perceptible. Plotinus, like Vedānta, affirms the existence of a positive ultimate reality—his 'The One' is not, like Buddhist emptiness, a negative 'nothingness,' but rather the source and foundation of all things.
The medieval German Christian mystic Meister Eckhart (1260-1328) went a step further—so far that the Catholic Church condemned certain of his teachings as heretical. Eckhart distinguishes between 'God' (Gott) and 'Godhead' (Gottheit). God is he who creates, sustains, loves—to whom Christians pray. But Godhead is that ineffable emptiness lying beyond God himself—the 'desert' (Wüste)—where there is no name, no attribute, no action. Eckhart has said: 'I pray God to rid me of God.' This utterance—the yearning to transcend even God—bears a striking resemblance to Buddhist emptiness. Yet Eckhart's 'desert' is, ultimately, a positive reality—'what remains even after all negation'—whereas Buddhist emptiness denies even that which remains.
The doctrine of the five sheaths (pañcakośa) described in the Taittirīya Upaniṣad (2.1-5) is a well-structured application of the neti neti method. Five sheaths or coverings—the food-sheath (the body, nourished by food), the life-sheath (vital force, breath), the mind-sheath (mind, thought and emotion), the intellect-sheath (intelligence, discernment, the faculty of decision), and the bliss-sheath (bliss, the peace of deep sleep)—the self is, as it were, wrapped in these five layers.