Here is a snip from an early draft of Kumarajiva's version of the Ten Grounds Sutra
. Vajragarbha Bodhisattva Mahasattva is teaching:
The path of the Buddhas, the lords among the Āryas,
is subtle, sublime, extremely difficult to comprehend,
and not such as can be realized through thought’s calculations,
As such, it is a region coursed in only by the wise.
Its essential nature, from its origins on forth to the present,
is quiescently still and devoid of any production or extinction.
From its origins on forth to the present, it is that emptiness
wherein all sufferings and torments are utterly extinguished.
It departs distantly beyond all of the destinies of rebirth
and is characterized by its identity with nirvāṇa itself.
In it, there is no middle and no end.
It is not such as can be described through words and phrases.
It transcends the three periods of time
and, in character, is comparable to empty space.
This region wherein the Buddhas course
is that of purity and profoundly quiescent cessation.
This is such as verbal descriptions find difficult to approach.
So too it is with the practices coursed in on the grounds.
If even describing them remains such a difficulty,
how much the more so would it be to reveal them to others.
The wisdom of the Buddhas
abandons the pathways accessible to the mental factors,
cannot be conceived of by thought or described in words, and
is not a place wherein aggregates, sense realms, or sense bases exist.
One can only come to know it through wisdom
as it is not such as can be reached as an object of the consciousnesses.
It is as difficult to describe as tracks of travel through the air.
How then could one succeed in revealing any characteristic marks?
The meanings associated with the ten grounds are just like this.
They are not such as a mind not boundlessly vast can ever know.
Although these matters are inherently difficult,
one brings forth vows, coursing thence in kindness and compassion.
One’s gradual fulfillment of practice on the ten grounds
is not such as one might arrive at through thought.
This sort of practice on the grounds
is subtle, sublime, and especially difficult to perceive.
One cannot know them through thought
and must take on the powers of the Buddhas to describe them.
You should all now attend to this with that reverence
wherein everyone joins together in listening single-mindedly.
A bodhisattva does not become weary of evil beings nor does he commit the error of bringing forth thoughts inclined to reject them and cast them aside. Avatamsaka Sutra, ch. 25