The descent from Supermind to Overmind signals the veiling of the pure and brilliant illumination of the Truth-Consciousness to create a gradation of awareness that, while remaining capable of experiencing and understanding the Oneness of all creation, nevertheless has now the ability to separate itself in an exclusive concentration of consciousness to work out the detailed possibilities of each line of action, for itself and as if it were separate from the rest of the creation.
This level therefore, while limiting the awareness and manifestation of the ultimate truth of existence, is not yet at a place where it actually falsifies the knowledge. One might say, rather, that it ignores the truth, rather than actively deceives. This separative knowledge and its effects of the denial of the unified whole of existence then gets worked out more completely, this time with less and finally no active awareness of the unity, as the consciousness moves into Mind, Life and Matter.
Eventually, in the depths of matter, there is a seeming inconscience where each form is fragmented and separated from each other form, but where there is no active self-awareness.
“Existence plunging into an apparent Non-Existence, Consciousness into an apparent Inconscience, Delight of existence into a vast cosmic insensibility are the first result of the fall and, in the return from it by a struggling fragmentary epxerience, the rendering of Consciousness into the dual terms of truth and falsehood, knowledge and error, of Existence into the dual terms of life and death, of Delight of existence into the dual terms of pain and pleasure are the necessary process of the labour of self-discovery.”
In any world formed by the process of veiling the unity and thereby creating a separative existence whose aim is to carry out the principle of its own existence and manifestation of its own possibilities, exclusive of any awareness of the Unity to which it belongs, it becomes necessary to work through these dualities.
reference: Sri Aurobindo, The Life Divine, Chapter 28, Supermind, Mind and the Overmind Maya