The Upanishads take us to the subtle realisation, one which underpins the action of the spiritual sense. The spiritual sense goes beyond even a knowledge by identity to an intrinsic “knowing” that is always present based on the entire universal creation as one conscious being. If the human being stubs his toe, he experiences the sensation immediately and intensely as part of his being. The universal being has the same type of immediate and intense form of knowing as the entire universe is His being.
The Upanishads tell us in a variety of ways about this status: “The Spirit who is here in man and the Spirit who is there in the Sun, lo, it is One Spirit and there is no other.” (Taittiriya Upanishad)
The Isha Upanishad directly links the Eternal Being with the manifested creation: “All this is for habitation by the Lord, whatsoever is individual universe of movement in the universal motion.” and “That moves and That moves not; That is far and the same is near; That is within all this and That also is outside all this. 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? It is He that has gone abroad–That which is bright, bodiless, without scar of imperfection, without sinews, pure, unpierced by evil. The Seer, the Thinker, the One who becomes everywhere, the Self-existent has ordered objects perfectly according to their nature from years sempiternal.” (Sri Aurobindo, The Upanishads, Isha Upanishad, pp. 19-21)
The Shwetashwatara Upanishad gets into more concrete detail: “Even as the spider that out of himself fashioneth his own web, so is God One and nought else existeth, but by his own nature covereth Himself up in the threads He has spun out of primal matter. … One God who alone is and He lurketh hidden in every creature, for He pervadeth and is the inmost Self of all beings…. One Eternal of all these that pass and are not, One conscious in all consciousnesses; He being One ordereth the desires of many; He alone is the great Source to which Sankhya and Yoga bring us.” (op. cit. pg. 380-381)
Then there is the famous peace chant that is associated with the Isha Upanishad: “Complete in itself is that yonder and complete in itself is that which is here and the complete ariseth from the complete; but when thou takests the complete from its fullness, that which remaineth is also complete.” (op cit. pg. 439)
As Sri Aurobindo concludes: “It is possible for us not only to know by conscious identity, by a spiritual comprehension of self, of principles and aspects, force, play and action, by a direct spiritual, supramental and intuitive thought knowledge, by the heart’s spiritually and supramentally illumined feeling, love, delight, but also to have in a very literal significance the sense– sense-knowledge or sensation– of the spirit, the self, the Divine, the Infinite. The state described by the Upanishad in which one sees, hears, feels, touches, senses in every way the Brahman and the Brahman only, for all things have become to the consciousness only that and have no other, separate or independent existence, is not a mere figure of speech, but the exact description of the fundamental action of the pure sense, the spiritual object of the pure Sanjnana.”
Sri Aurobindo, The Synthesis of Yoga, Part Four: The Yoga of Self-Perfection, Chapter 24, The Supramental Sense , pg. 834