Analysis Regarding the Existence and Nonexistence of Meditative Stability (bSam gtan yod med thaggcod) says:

In wholeness, the essential heart, which is mind nature,

Both presence and absence of meditation are contradictions

Its presence, a superimposition due to calmness

Its absence, a nihilist’s detraction.

If neither, indefinite and undemonstrable.

The Great Garuda states:

The implications of the threefold encounter-the display that manifests as an objective field of experience can be discerned within the “interval” between sense objects and mind, with nothing that arises being rejected.

Just as myriad dreams are subsumed within sleep, being natural manifestations that are empty and without true existence, so too the phenomena of the universe, whether of samsara or nirvana, are embraced by mind. They manifest within mind, the vast expanse, but have no substance.

The nature of mind alone is the seed of everything. Anything in conditioned existence or nirvana unfolds from it. Homage to mind, which is like the wish-fulfilling gem that grants the fruition of one’s desires. –The Treasury of Songs of Realization

And Naturally Arising Awareness states: Like mirages or shifting images on water, things are not simply nonexistent, nor are they existent. Because they are beyond both existence and nonexistence, there is no recollection of them in the mind of one who is realized. The essence of awareness is unborn. The nature of apparent phenomena is unceasing. The defining characteristic of awareness is its insubstantiality. The fruition of that awareness is uncontrived.

Although the single naturally occurring state creates all samsara and nirvana, without anyone creating awareness, which is the source, it abides like space, beyond deliberate effort. With this metaphor and its underlying meaning in harmony, all value judgments concerning diverse phenomena are pacified within the vast expanse of a single basic space. Within the ultimate heart essence, which transcends existence and nonexistence, all phenomena are unceasing, and regardless of the display that arises their very essence is the unimaginable and inexpressible expanse. This is truly beyond all conventional expression and description.