Now, in terms the emptiness of the internal, it was said:

This being what their nature is,
The eye is empty of the eye –
The same is true for ears and nose,
For tongue, for body and the mind. (6.181)

They neither last nor disappear.
Hence all these six, the eyes and such,
Possess no nature of their own.
This is the inner emptiness. (6.182)

To give a brief quote:

Which internal things are indicated by the emptiness of the internal? The eyes, ears, nose tongue, body and mind are the internal. These do not constantly remain, nor do they disappear; eye is therefore empty of eye. Why? Because that is its nature.¹

For things to constantly remain² would mean they wouldn’t lose their nature. Since they also remain for time a before changing, it is stated that they ‘don’t just disappear.’ As these statements show, any entity having a nature would by necessity be neither constantly remaining nor simply disappearing. As stated:

A true nature originating due to causes
And conditions, is not tenable.
A true nature coming from causes
And conditions would be fabricated.

And how could it be acceptable to say
That a true nature is something created?
A true nature cannot be something created,
And cannot not rely on anything else.³

One may ask whether a nature as specified by the Master in the Treatise exists as it is asserted by the Master? As the Illustrious One taught it:

Whether the tathāgatas appear or not, the nature of reality remains the same.

When it says the nature of reality, whatsoever that may be, it is the nature of the eyes and so forth. And what is their nature? It is that which is unfabricated and not reliant on others, the nature itself that is realised by a mind that is free from the cataracts of ignorance. And if one asks whether this is something existent or non-existent? If it doesn’t exist, for what purpose do the bodhisattvas practice the path of the perfections? It is precisely in order to realise this reality of things that the bodhisattvas undergo all of these immense hardships. As is stated:

O son of good family. The ultimate does not arise, does not cease, does not disappear, does not come, does not go, and cannot be expressed in words. It cannot be put into words and cannot be conceptualised. The ultimate, O son of good family, is something ineffable known through the discriminative wisdom of noble ones who are at peace. The ultimate, O son of good family, is unaffected by whether tathāgatas appear or not; by whether bodhisattvas shave off their hair and beards, don the saffron robes, leave householder life with genuine faith and go forth into homelessness for the sake of it; nor after having gone forth by their degree of diligence they demonstrate, as if their hair or robes were on fire, in order to attain this reality of things. If, son of good family, the ultimate did not exist, a life of purity would be meaningless, and it would be pointless for the tathāgatas to appear. Since the ultimate exists, bodhisattvas can be said to be knowledgeable about the ultimate.⁴

Some might react to this, saying, ‘My word! Not agreeing that it is anything at all, and still professing it to be a nature that is an accidental unfabricated something that does not rely on anything else; your assertions are completely contradictory!’

Let me explain. You haven’t understood the point the Treatise is making. Its intent is this: If the interdependently arisen nature of the eyes and so forth was of the nature that immature beings perceive them to be, that nature would be something mistakenly understood, and a life of purity would then be meaningless. But since this is not its real nature, to find out what that is, a life of purity has meaning. It is from the perspective of the relative that we express it to be unfabricated and not dependent on anything else. And this, which immature beings cannot see, is considered the nature. And being in that fashion, the ultimate is neither an existent thing nor a non-existent thing, since it is by nature pacified. And the Master does not only assert this nature for himself, but as this point can potentially be convincing to others, this nature is presented as something provable to both parties.

Some say that the nature of something like fire is that it is hot and so forth, but this is completely unacceptable, because in being interdependently arisen it is something artificial and reliant. It does not make sense to say that since it is something existent it does not have artifice and is not reliant on something else, because when there is a relationship of attributes it is not something with any conclusive reality, and such aspects have relevance on the relative level. But enough digression. We shall now return to the main topic.

By saying that the eyes and so forth are empty of being eyes and so forth, their emptiness of a true nature has been made clear. It is not an emptiness of one thing being empty of another, as if saying that the eye is empty because it has no inner creator, or is empty of a real dualism of subject and object.

As for emptiness of the external:

This being how their nature is,
A form is empty of a form.
And this is true of sound and smell,
Taste, texture and phenomena. (6.183)

That form and such are nature-less,
This is the outer emptiness.

As stated:

What is emptiness of the external? What we call external phenomena are forms … [and so forth]. These do not remain constantly nor do they disappear, and form is therefore empty of form, because that is its nature.⁵

That what is both is nature-less,
Is outer-inner emptiness. (6.184)

As stated:

That external internal phenomena have no inherent nature as external internal phenomena, is what we call external internal emptiness. …⁶

That everything is nature-less
Is what the wise term emptiness.
This voidness too is empty of
A nature which is emptiness. (6.185)

The voidness of the void is termed
The emptiness of emptiness.
And this was taught to stop the mind
That clings to emptiness as real. (6.186)

As stated:

What is the emptiness of emptiness? The emptiness of emptiness is the emptiness which is empty of the emptiness that is all phenomena’s emptiness.⁷

This was taught to counteract the clinging of those who believe emptiness to be something real. As stated:

To defeat all conceptual ideas
You taught the nectar of emptiness.
But you severely reproached those
Who ended up clinging to that.⁸

The universe and all that live
Pervade throughout; it’s infinite
Just like the four immeasurables;
Hence the immensity of space. (6.187)

The worlds of the beings and the environment are not found anywhere other than in the directions of space, which means space completely pervades all that live. The directions of space are therefore immense. When meditating on love and so forth one does so through extending it throughout the directions, which serves as an example for the immeasurability of the directions, showing how boundless it is, and therefore immense.

The emptiness of space with ten
Directions is the emptiness
Of the immensity, thus taught
To block thoughts of immensity. (6.188)

As stated:

What is the emptiness of immensity? The eastern direction is empty of the eastern direction. …⁹

The emptiness of immensity was taught to counteract belief in the immensity of space for those who think space is immeasurable. The Vaiśeṣikas do consider the directions of space to be something substantial in this way.

Nirvana is the ultimate
Because it is the highest goal.
That that is empty of itself
Is voidness of the ultimate. (6.189)

To counter all conceptions of
Nirvana being something real,
The Knower of the Ultimate
Taught voidness of the ultimate. (6.190)

As stated:

What is the emptiness of the ultimate? The ultimate refers to nirvana. Since it neither constantly remains nor disappears, nirvana is empty of nirvana. …¹⁰

This was taught to counteract the clinging of those who believe nirvana to be something real. The word parama¹¹ denotes the objective or that which is to be understood.