The thinking human being functions in what we may call the rational consciousness, but is nevertheless affected, influenced and even controlled in many movements of his being by those powers of consciousness which are above the range of the reason, which he calls suprarational, as well as those which are below the range of the reason, which he calls infrarational. Just as human eyesight operates within a certain range of frequencies, or human hearing operates within a fixed range of frequencies, which ranges do not define the entirety of the potentially visible or audible universe, so also the reasoning faculty does not entirely define the powers of knowledge in existence.
Sri Aurobindo observes the functioning of these three powers: “The spiritual or suprarational is always turned at its heights towards the Absolute; in its extension, living in the luminous infinite, its special power is to realise the infinite in the finite, the eternal unity in all divisions and differences. Our spiritual evolution ascends therefore through the relative to the absolute, through the finite to the infinite, through all divisions to oneness. Man in his spiritual realisation begins to find and seize hold on the satisfying intensities of the absolute in the relative, feels the large and serene presence of the infinite in the finite, discovers the reconciling law of a perfect unity in all divisions and differences. The spiritual will in his outer as in his inner life and formulation must be to effect a great reconciliation between the secret and eternal reality and the finite appearances of a world which seeks to express and in expressing seems to deny it. Our highest faculties then will be those which make this possible because they have in them the intimate light and power and joy by which these things can be grasped in direct knowledge and experience, realised and made normally and permanently effective in will, communicated to our whole nature.”
“The infrarational, on the other hand, has its origin and basis in the obscure infinite of the Inconscient; it wells up in instincts and impulses, which are really the crude and more or less haphazard intuitions of a subconscient physical, vital, emotional and sensational mind and will in us. Its struggle is towards definition, towards self-creation, towards finding some finite order of its obscure knowledge and tendencies. But it has also the instinct and force of the infinite from which it proceeds; it contains obscure, limited and violent velleities that move it to grasp at the intensities of the absolute and pull them down or some touch of them into its finite action: but because it proceeds by ignorance and not by knowledge, it cannot truly succeed in this more vehement endeavour.”
“The life of reason and intelligent will stands between that upper and this nether power. On one side it takes up and enlightens the life of the instincts and impulses and helps it to find on a higher plane the finite order for which it gropes. On the other side it looks up towards the absolute, looks out towards the infinite, looks in towards the One, but without being able to grasp and hold their realities; for it is able only to consider them with a sort of derivative and remote understanding, because it moves in the relative and, itself limited and definite, it can act only by definition, division and limitation.”
“These three powers of being, the suprarational, rational and infrarational are present, but with an infinitely varying prominence in all our activities.”
Sri Aurobindo, The Human Cycle: The Psychology of Social Development, Chapter 13, Reason and Religion, pp. 127-129