That's the million dollar question
Mūlamadhyamakakārikā wrote:
(Nagarjuna)
“The Transcendent Conqueror has taught
That all deceptive phenomena are false.
All conditioned phenomena are deceptive,
And, therefore, they are false. [XIII.1]
If a phenomenon that is deceptive is also false,
Then what is it that deceives?
With this, the Transcendent Conqueror
Has fully revealed emptiness. [XIII.2]
(Opponent)
Things are devoid of essence
Because they are perceived to change.
There are no entities without essence
Because entities possess emptiness. [XIII.3]
(Nagarjuna)
If there is no essence,
To what does change pertain?
If there were essences,
How could there be change? [XIII.4]
Change is not in that itself,
Nor is it in something else,
Because the young do not age,
And because the aged do not age. [XIII.5]
If that itself changes,
Then milk itself is yogurt.
What, other than milk,
Would turn into yogurt? [XIII.6]
If there were a bit of something that is not empty,
There could be a bit of something that is empty.
As there is not a bit that is not empty,
How could there be anything that is empty? [XIII.7]
The Victorious Ones have taught emptiness
As a deliverance from all views.
“For those whose view is emptiness, they teach,
Nothing can be accomplished. [XIII.8]”
Mabja Jangchub Tsondru. “Ornament of Reason: The Great Commentary to Nagarjuna's Root of the Middle Way.”