The mental consciousness starts from perceived parts and, when it tries to build up a complete picture, it does so through aggregation of those parts. This is a weakness in the capacity of the mental awareness to grasp the transcendental and universal aspects of reality. It treats its own individual standpoint as something separate and divided from everything else, and thereby sets up an opposition and battle for the individual to survive and thrive as against the rest of the universe! Indeed, the mental consciousness also has no sense of the unity of the flow of Time and thus, tries to segment the unfolding manifestation according to the artificial divisions of time that have been devised for the practical operation of the social order based on the human mental capacities of organization.
Sri Aurobindo elaborates: “Mind cannot arrive at identity with the Absolute even when by a stretch of the intellect it conceives the idea, but can only disappear into it in a swoon or extinction; it can only have a kind of sense or an intimation of certain absolutes which it puts by the mental idea into a relative figure. It cannot grasp the universal, but only arrives at some idea of it through an extension of the individual or a combination of apparently separate things and so sees it either as a vague infinite or indeterminate or a half determined largeness or else only in an external scheme or constructed figure. The indivisible being and action of the universal, which is its real truth, escapes the apprehension of the mind, because the mind thinks it out analytically by taking its own divisions for units and synthetically by combinations of these units, but cannot seize on and think entirely in the terms, through it may get at the idea and certain secondary results, of the essential oneness. It cannot, either, know truly and thoroughly even the individual and apparently separate thing, because it proceeds in the same way, by an analysis of parts and constituents and properties and a combination by which it erects a scheme of it which is only its external figure.”
As a result, the mind is fixed on the outer forms and not the inner sense which means the essential unity of all existence always escapes the mental awareness.
“And all this which is impossible for the mind to do, but possible only to strive towards and figure, is inherent and natural to the supramental knowledge.”
Sri Aurobindo, The Synthesis of Yoga, Part Four: The Yoga of Self-Perfection, Chapter 19, The Nature of the Supermind, pp. 758-759