"The nature of mind as the element of space does not [depend upon] causes or conditions, nor does it [depend on] a gathering of these.
It has neither arising, cessation, nor abiding.

This clear and luminous nature of mind is as changeless as space.
It is not afflicted by desire and so on, the adventitious stains, which are sprung from incorrect thoughts.

It is not brought into existence by the water of karma, of the poisons, and so on.
Hence it is also not consumed by the cruel fires of dying, falling sick, and aging."

Mahāyānottaratantra Śāstra;