As the overmental consciousness becomes established in the nature, it has a natural uplifting and widening effect on Matter, Life and Mind. In turn, the development of higher potentialities and elimination of the extremes of the Inconscience more and more prepares for the next phase of the ascent up the stairway of consciousness. Because the overmental consciousness obtains its light as a reflection or diffused result of the original supramental light, there comes a time when the supramental force can work more powerfully and directly on the nature. Sri Aurobindo describes this process: “This would continue until the point was reached at which Overmind would begin itself to be transformed into Supermind; the supramental consciousness and force would take up the transformation directly into its own hands, reveal to the terrestrial mind, life, bodily being their own spiritual truth and divinity and, finally, pour into the whole nature the perfect knowledge, power, significance of the supramental existence. The soul would pass beyond the borders of the Ignorance and cross its original line of departure from the supreme Knowledge: it would inter into the integrality of the supramental gnosis; the descent of the gnostic Light would effectuate a complete transformation of the Ignorance.”
Sri Aurobindo, The Life Divine, Book 2, Part 2, Chapter 26, “The Ascent Towards Supermind”