However, in the context of wisdom and compassion, wisdom can simply be put as realization of emptiness, which encompasses many meanings: realization of no-self, of emptiness pertaining to Madhyamaka of the exoteric school, and realization of Great Emptiness and Clear Light. From the point of view of the esoteric Buddhism, which also includes the view of the Great Perfection, emptiness and clear light are one and the same.
The term “Great Emptiness” has never appeared in the history of man’s thought and literature. And even if it did, it was only to mean the void as a result of matter being decomposed to decreasing size of particles until it could decompose no more. Some people now still do not dare to affirm even this void, insisting rather that energy should remain at the end. (Energy is matter too.) If energy also ends in a state of emptiness, it will be as if all matter were born from nothing. This, to many, is an unacceptable conclusion. So what these people are able to comprehend is even less than that of the exoteric school.
~ Depicted from Buddhism - The Definition