The seers and sages of the Upanishads consistently tell us that one cannot describe the Reality, the Brahman, the Eternal by any specific mental conception. They warn us “not this, not that” so that we do not limit or circumscribe the reality that goes so far beyond any definition we can provide, or any specific manifestation of forms. If we just look at this statement, however, it is easy to fall into the idea that the Supreme Divine is only to be understood as separate and different from the manifested universe. It is essential that we therefore look at the other Upanishadic statements that modify this concept. We add therefore the idea that the Brahman is “One without a second.” This statement implies an omnipresent Reality, and this concept is further clarified with the statement “All this is the Brahman.”. Putting all three together, we avoid the extremes that lead to either an illusionist view of the universe, or which lead to the abandonment of the life of the world as something “other” or “lesser” than the impersonal, unmoving Brahman.
Sri Aurobindo clarifies this further: “The supreme being of the Divine is beyond manifestation: the true sempiternal image of him is not revealed in matter, nor is it seized by life, nor is it cognizable by mind…. What we see is only a self-created form, rupa, not the eternal form of the Divinity, svarupa. There is someone or there is something that is other than the universe, inexpressible, unimaginable, an ineffably infinite Godhead beyond anything that our largest or subtlest conceptions of infinity can shadow. All this weft of things to which we give the name of universe, all this immense sum of motion to which we can fix no limits and vainly seek in its forms and movements for any stable reality, any status, level and point of cosmic leverage, has been spun out, shaped, extended by this highest Infinite, founded upon his ineffable supracosmic Mystery. It is founded upon a self-formulation which is itself unmanifest and unthinkable.”
The sum of all manifested creatures and forms cannot equal the supreme Divine, and they do not contain the Divine, nor limit and define the Divine in its entirety. They are contained within the larger being of the Supreme. “In the unthinkable timeless and spaceless infinity of his existence he has extended this minor phenomenon of a boundless universe in an endless space and time.”
Sri Aurobindo, Essays on the Gita, Second Series, Part I, Chapter 5, The Divine Truth and Way, pp. 297-298