Sri Aurobindo, The Life Divine, p. 889
"If it is the sole intention of Nature in the evolution of the spiritual man to awaken him to the supreme Reality and release him from herself, or from the Ignorance in which she as the Power of the Eternal has masked herself, by a departure into a higher status of being elsewhere, if this step in the evolution is a close and an exit, then in the essence her work has been already accomplished and there is nothing more to be done. The ways have been built, the capacity to follow them has been developed, the goal or last height of the creation is manifest; all that is left is for each soul to reach individually the right stage and turn of its development, enter into the spiritual ways and pass by its own chosen path out of this inferior existence.
But we have supposed that there is a farther intention, – not only a revelation of the Spirit, but a radical and integral transformation of Nature. There is a will in her to effectuate a true manifestation of the embodied life of the Spirit, to complete what she has begun by a passage from the Ignorance to the Knowledge, to throw off her mask and to reveal herself as the luminous Consciousness-Force carrying in her the eternal Existence and its universal Delight of being. It then becomes obvious that there is something not yet accomplished, there becomes clear to view the much that has still to be done, bhuri aspasta kartvam; there is a height still to be reached, a wideness stiff to be covered by the eye of vision, the wing of the will, the self-affirmation of the Spirit in the material universe. What the evolutionary Power has done is to make a few individuals aware of their souls, conscious of their selves, aware of the eternal being that they are, to put them into communion with the Divinity or the Reality which is concealed by her appearances: a certain change of nature prepares, accompanies or follows upon this illumination, but it is not the complete and radical change which establishes a secure and settled new principle, a new creation, a permanent new order of being in the field of terrestrial Nature. The spiritual man has evolved, but not the supramental being who shall thenceforward be the leader of that Nature".
There is so much packed in this paragraph that we need to differentiate many strengths in this statement. To state very briefly it can be said that in the history of the world, man has been seeking and as a result of this search he has discovered something and what he has discovered is satisfying but only to some extent. There is still much more to be done and in Sri Aurobindo's words "the spiritual man has come but not the supramental being". That is to say the human being who is a mental man, thinks with the mind, acts with the mind, decides with the mind, executes with the mind and from that point of view, some people have reached to a level of spiritual existence and they have been able to find out the ways and means by which one can rise from the mental level to the spiritual. If the intention was only this much then that work has been done, the ways have been found out and it is now for the rest to follow them out, to work this out in their being. But this is not so. The spiritual man has come but not the Supramental being, so there is a distinction made between spiritual and the Supramental. So there are three words to be distinguished: the mental, the spiritual and the Supramental. If you understand these three words separately, then we shall be able to grasp exactly what is meant here because it is said, the mental being has become the spiritual, at least in some cases, but the supramental being has not yet come into being.