One may observe that horses many times have their peripheral vision shielded with blinders in order to prevent them from going away from the intended path through any form of distraction. The human reason is very much like this horse in the sense of creating walls within which the individual allows it to operate, generally related to specific tasks, goals or objectives in the material world that are sought to be achieved. This type of exclusive concentration is very powerful, yet it has limitations for arriving at a greater truth or understanding a greater reality which lies outside the self-imposed limits.
Sri Aurobindo notes: “The highest power of reason, because its pure and characteristic power, is the disinterested seeking after true knowledge. When knowledge is pursued for its own sake, then alone are we likely to arrive at true knowledge. Afterwards we may utilise that knowledge for various ends; but if from the beginning we have only particular ends in view, then we limit our intellectual gain, limit our view of things, distort the truth because we cast it into the mould of some particular idea or utility and ignore or deny all that conflicts with that utility or that set idea. By so doing we may indeed make the reason act with great immediate power within the limits of the idea or the utility we have in view, just as instinct in the animal acts with great power within certain limits, for a certain end, yet finds itself helpless outside those limits. It is so indeed that the ordinary man uses his reason — as the animal uses his hereditary, transmitted instinct — with an absorbed devotion of it to the securing of some particular utility or with a useful but hardly luminous application of a customary and transmitted reasoning to the necessary practical interests of his life. Even the thinking man limits his reason to the working out of certain preferred ideas, he ignores or denies all that is not useful to these or does not assist or justify or actually contradicts or seriously modifies them, — except in so far as life itself compels or cautions him to accept modifications for the time being or ignore their necessity at his peril.”
“He follows most commonly some interest or set of interests; he tramples down or through or ignores or pushes aside all truth of life and existence, truth of ethics, truth of beauty, truth of reason, truth of spirit which conflicts with his chosen opinions and interests; if he recognises these foreign elements, it is nominally, not in practice, or else with a distortion, a glossing which nullifies their consequences, perverts their spirit or whittles down their significance. It is this subjection to the interests, needs, instinct, passions, prejudices, traditional ideas and opinions of the ordinary mind which constitutes the irrationality of human existence.”
Sri Aurobindo, The Human Cycle: The Psychology of Social Development, Chapter 11, The Reason as Governor of Life, pp. 106-107