At the core of the mental awareness is the ego-consciousness. The ego identifies itself as a separate being and lives in a fragmented and divided universe made up of multiple ego-personalities and separate names and forms. The ego erects the walls and barriers that prevent the individual from perceiving and experiencing the oneness of all creation. In the transition to the gnostic consciousness, this dividing and fragmenting ego-consciousness must be put aside in order that the true oneness and unity of the entire creation can assume its true role as the foundation of the gnostic awareness.
Sri Aurobindo observes: “This truth of things at which we must arrive before we can enter into the gnosis,–for in that all exists and from that all originates on the gnostic plane,–is, first of all, a truth of unity, of oneness, but of unity originating diversity, unity in multiplicity and still unity always, an indefeasible oneness. State of gnosis, the condition of vijnanamaya being, is impossible without ample and close self-identification of ourselves with all existence and with all existences, a universal pervasiveness, a universal comprehension or containing, a certain all-in-allness. The gnostic Purusha has normally the consciousness of itself as infinite, normally too the consciousness of containing the world in itself and exceeding it; it is not like the divided mental being normally bound to a consciousness that feels itself contained in the world and a part of it.”
“The least reversion to ego-thought, ego-action, ego-will brings back the consciousness tumbling out of such gnostic Truth as it has attained into the falsehoods of the divided mind-nature. A secure universality of being is the very basis of this luminous higher consciousness. Abandoning all rigid separateness (but getting instead a certain transcendent overlook or independence) we have to feel ourselves one with all things and beings, to identify ourselves with them, to become aware of them as ourselves, to feel their being as our own, to admit their consciousness as part of ours, to contact their energy as intimate to our energy, to learn how to be one self with all. That oneness is not indeed all that is needed, but it is a first condition and without it there is no gnosis.”
The Isha Upanishad states it succinctly: “But he who sees everywhere the Self in all existences and all existences in the Self, shrinks not thereafter from aught. He in whom it is the Self-Being that has become all existences that are Becomings, for he has the perfect knowledge, how shall he be deluded, whence shall he have grief who sees everywhere oneness?” (Sri Aurobindo, The Upanishads, Isha Upanishad, v. 6-7, pg. 21)
Sri Aurobindo, The Synthesis of Yoga, Part Two: The Yoga of Integral Knowledge, Chapter 23, The Conditions of Attainment to the Gnosis, pp. 469-470