The mind is limited in its ability to understand forces and states of consciousness that function outside of its normal frame. At the same time, it does have the ability to get a “sense” of things beyond its own sphere through the process of extrapolating from effects and through means of expanding its normal frame of experience. For example, our vision is limited by the narrow range of the visible spectrum. Yet we know that there is spectrum above and below our normal range. Some of this is due to instruments we have created to measure these ranges, and some due to filters and the determination of effects that take place despite filtering the visible spectrum; in other words, through the effect produced that cannot be explained by the normal direct cause and effect of what can be seen.
The Isha Upanishad notes that “The face of Truth is covered with a brilliant golden lid; that do thou remove, O Fosterer, for the law of the Truth, for sight.” (Sri Aurobindo, The Upanishads, Isha Upanishad, v. 15, pg. 23) The implication here is that the mind cannot directly see the higher truth, but that it becomes possible to view this Truth if the barrier is removed.
The Taittiriya Upanishad describes the levels beyond the mind as the “knowledge-sheath” and the “bliss-sheath” and these are able to be cognized through a process of concentration of thought, tapasya.
Sri Aurobindo observes: “Yet it is necessary to attempt some account of their principles and practical effect so far as they can be grasped by the mind that stands on the border of the two hemispheres. The passage beyond that border would be the culmination, the completeness of the Yoga of self-transcendence by self-knowledge. The soul that aspires to perfection, draws back and upward, says the Upanishad, from the physical into the vital and from the vital into the mental Purusha,–fro mthe mental into the knowledge-soul and from that self of knowledge into the bliss Purusha. This self of bliss is the conscious foundation of perfect Sachchidananda and to pass into it completes the soul’s ascension. The mind therefore must try to give to itself some account of this decisive transformation of the embodied consciousness, this radiant transfiguration and self-exceeding of our ever-aspiring nature. The description mind can arrive at, can never be adequate to the thing itself, but it may point at least to some indicative shadow of it or perhaps some half-luminous image.”
Sri Aurobindo, The Synthesis of Yoga, Part Two: The Yoga of Integral Knowledge, Chapter 21, The Ladder of Self-Transcendence, pp. 454-455