.
Emptiness thus becomes a fundamental characteristic of
Mah
y
na
Buddhism. The teaching is subtle and its precise formulation a matter of sophisticated debate, since the slightest misunderstanding is said to obstruct progress towards final liberation. Emptiness is never a generalized vacuity, like an empty room, but always relates to a specific entity whose emptiness is being asserted. In this way up to twenty kinds of emptiness are recognized, including the emptiness of emptiness. The necessary indiscoverability of essences is the M
dhyamakan emptiness. It is important to distinguish this from
nihilism
. In Yog
c
ra (
Vijñ
nav
da
), emptiness is taught as the inability to think of an object apart from the consciousness which thinks of that object, i.e. the necessary indissolubility of subject and object in the process of knowing is the Yog
c
rin emptiness. It is important to distinguish this from idealism and solipsism.