When we examine the operation of sense perception, we generally treat the senses as extensions of the mind. Whether it is sight, hearing, smell, taste or touch, we recognise the senses as receiving the impressions of the material world, translating them into nervous impulses which are routed to the brain, where the mental interpretation of what was experienced takes place. Sense perception can break down at any stage of this process and in such cases we diagnose someone as being blind, deaf etc. Some Western psychologists, studying the issue, have pointed out that we do not have a direct experience of the material world as the process involves several steps of translation of whatever impinged upon the senses into a form of electrical-chemical energy into some understanding in the mind. Yet there are experiences that seem to transcend the action of the physical senses, and even those that go beyond the conscious experience in the mind, which lead us to appreciate that this basic understanding is severely limited and incomplete.
The Kena Upanishad took up the relation of the senses and the mind, and the wider context of experiencing life in the world. Verses 6 and 7 directly take up the question of sense perception in its true sense:
“That which sees not with the eye, that by which one sees the eye’s seeings, know That to be the Brahman and not this which men follow after here. That which hears not with the ear, that by which the ear’s hearing is heard, know That to be the Brahman and not this which men follow after here.”
Sri Aurobindo notes: “Sense, however, is not or does not appear to be fundamental; it is only an instrumentation of Mind using the nervous system. It is not even a pure mental functioning, but depends so much upon the currents of the Life-force, upon its electric energy vibrating up and down the nerves, that in the Upanishads the senses are called Pranas, powers or functionings of the Life-force. It is true that Mind turns these nervous impressions when communicated to it into mental values, but the sense-action itself seems to be rather nervous than mental. In any case there would, at first sight, appear to be no warrant in reason for attributing a Sense of the sense to that which is not embodied, to a supramental consciousness which has no need of any such instrumentation.”
“But this is not the last word about sense; this is only its outward appearance behind which we must penetrate. … In its functioning, if we analyse that thoroughly, we see that it is the contact of the mind with an eidolon of Matter, — whether that eidolon be of a vibration of sound, a light-image of form, a volley of earth-particles giving the sense of odour, an impression of rasa or sap that gives the sense of taste, or that direct sense of disturbance of our nervous being which we call touch. … the mind operates upon Matter not directly, but through the Life-force; that is its instrument of communication and the Life-force, being in us a nervous energy and not anything material, can seize on Matter only through nervous impressions of form, through contactual images, as it were, which create corresponding values in the energy-consciousness called int he Upanishads the Prana. Mind takes these up and replies to them with corresponding mental values, mental impressions of form, so that the thing sensed comes to us after a triple process of translation, first the material eidolon, secondly the nervous or energy-image, third the image reproduced in stuff of mind.”
Sri Aurobindo, The Upanishads, Kena Upanishad and analysis, pg. 102, 142-155