The Notion of
Shunyata - Emptiness
The next important concept is the notion of sunyata, which means emptiness. Sunyata normally has a negative connotation, meaning things do not have any inherent existence or do not have any substantiality. The lack of that substantiality is emptiness. In Yogacara philosophy, emptiness begins to assume a positive connotation. This is also true in tantra. Emptiness is no longer regarded as the total negation of the substantiality of things. In fact, emptiness begins to assume the role of being the absolute, the ground upon which the phenomenal world functions and exists. So, it becomes an affirmation of negation. That is very interesting, because normally, if you negate something, that's the end of it. In the Yogacarin and tantric concept, negation itself becomes the affirmation of something that we don't normally have access to. It is a reality that can be perceived and tuned into, not through ordinary means of knowledge, but through a higher form of knowledge. As you begin to transform your negativities into something positive and higher, then, as you proceed, you also begin to apprehend reality or sunyata in a much more precise way
In tantra, sunyata is even called the unshakable vajra. It's so real and solid that we can't deny its existence. To say that in strict Madhyamikan terms would be shocking. When the chair you sit on is insubstantial and the glass that you drink from is insubstantial, how could emptiness, which you can't even see, be more solid and real than what we are experiencing now? Tantrikas and Yogacarins almost, in some ways, substantialise the notion of emptiness. It becomes the ground or the reality upon which the phenomenal or relative world exists.