Briefly stated, if we accept that the world of Matter is all there is, then there is no way for the seeker to transcend it within the framework of this world. That leaves salvation either as an illusory and transitory sense of the mind, still bound within the framework of nature; or else, it puts off salvation for some other world after we depart this one. The soul’s intuition, and the experience of those who have achieved liberation, however, tells us that Matter is not the only formation which exists in the universe, and thus, other poises and statuses of consciousness become possible, and thus, the evolution of consciousness can become a reality.
In the Taittiriya Upanishad, the young seeker Bhrigu undertakes a course of intense tapasya, and explores the various potential bases of existence, first determining that Matter was the true reality and basis, but eventually recognizing additional principles or poises of consciousness including the vital plane in the form of Prana, the mental plane, the knowledge plane, and the bliss plane. These planes represent specific principles and relations of interaction and powers that vary from one to the other. Elsewhere they are referred to as “sheaths” (“koshas”) as they can be found all active within the human being in every more subtle energetic bodies.
Sri Aurobindo states the case for the requirement of understanding these planes of existence: “If the Purusha in us has thus to become by union with its highest self, the Divine Purusha, the knower, lord, free enjoyer of its Prakriti, it cannot be done, evidently by dwelling on the present plane of our being; for that is the material plane in which the reign of Prakriti is complete; there the divine Purusha is entirely hidden in the blinding surge of her activities, in the gross pomp of her workings, and the individual soul emerging from her involution of spirit in matter, subject in all its activities to its entangling in the material and vital instruments is unable to experience the divine freedom.”
The sense of freedom that we experience in the mind, as Sri Aurobindo concludes, is still a subtle form of bondage to the working of Nature. “Therefore we have had to speak of different planes of our consciousness and of the spiritual planes of the mental being; for if these did not exist, the liberation of the embodied being would have been impossible here on earth. He would have had to wait and at most to prepare himself for seeking it in other worlds and in a different kind of physical or spiritual embodiment less obstinately sealed in its shell of material experience.”
The shift from the “human standpoint” to the “divine standpoint” is essentially the shift of the conscious awareness from the material plane to the spiritual plane, and this is the leverage that is required to effect the transformation in the Nature called for in the integral Yoga.
Sri Aurobindo, The Synthesis of Yoga, Part Two: The Yoga of Integral Knowledge, Chapter 19, The Planes of Our Existence, pg. 427