The following is respectfully quoted from “The Nyingma School of Tibetan Buddhism” by His Holiness Dudjom Rinpoche:
Although all these phenomena are compounded internally by the mind, their apparitional aspect and supporting foundation are the five gross elements of which external objects are compounded, and which are caused, conditioned, supported and substantiated by the fourfold process of creation, duration, destruction and dissolution. As the number of mental propensities through which they appear as objects expands, the world realm of desire containing the four continents, Mount Sumeru and perimeter appears like a dream, along with the realm of form, which originates from the contemplation of the summit of existence, and so on. In brief, the entire array of the inanimate container and animate creatures, mobile and motionless, subsumed by the three world realms, does not appear in the ultimate vision of sublime beings. Rather, it is an apparitional mode of the bewildered intellect of sentient beings, which appears by the power of the subject-object dichotomy lapsing into delusion, like water in a mirage, and into erroneous perception, like seeing a mulicoloured rope as a snake. As it is said in the Pearl Necklace (mu-tig phreng-ba, NGB Vol.9):
In this way, the diverse appearances
Resemble a rope when seen as a snake.
Though not so, by clinging to them as such
The outer container and inner essence
Are established as duality.
The rope itself, on further investigation,
Is primordially empty of container and essence.
The ultimate takes form as relative.
That perception of the snake is visually true,
The perception of the rope is genuinely true.
Enduring, for example, as a bird relates to a scarecrow,
The independent existence of the two truths
Refers only to the relative world.
It has no relation to genuine reality.
Because of the expanse of emptiness
The essence of that [reality] is that all is free.