Sri Aurobindo
Letters of Sri Aurobindo
Volume I - Part 5
It is necessary to understand clearly the difference between the evolving soul (psychic being) and the pure Atman, self or spirit. The pure self is unborn, does not pass through death or birth, 
is independent of birth or body, mind or life or this manifested Nature. It is not bound by these things, not limited, not affected, even though it assumes and supports them. The soul, on the contrary, is something that comes down into birth and passes through death – although it does not itself die, for it is immortal – from one state to another, from the earth-plane to other planes and back again to the earth-existence. It goes on with this progression from life to life through an evolution which leads it up to the human state and evolves through it all a being of itself which we call the psychic being. This being supports the evolution and develops a physical, a vital, a mental human consciousness as its instruments of world-experience and of a disguised, imperfect, but growing self-expression. All this it does from behind a veil, showing something of its divine self only in so far as the imperfection of the instrumental being will allow it. But a time comes when it is able to prepare to come out from behind the veil, to take command and turn all the instrumental nature towards a divine fulfilment. This is the beginning of the true spiritual life. The soul is able now to make itself ready for a higher evolution of manifested consciousness than the mental human – it can pass from the mental to the spiritual and through degrees of the spiritual to the supramental state. Till then, till it has reached the spiritual realisation, there is no reason why it should cease from birth, it cannot in fact so cease. If having reached the spiritual state, it wills to pass out of the terrestrial manifestation, it may indeed make such an exit,– but there is also possible a higher manifestation, in the Knowledge and not in the Ignorance.
Your question therefore does not arise. It is not the naked spirit, but the psychic being that goes to the psychic plane to rest till it is called again to another life. There is therefore no need of a Force to compel it to take birth anew. It is in its nature something that is put forth from the Divine to support the evolution and it must do so till the Divine’s purpose in its evolution is accomplished. Karma is only a machinery, it is not the fundamental cause of terrestrial existence – it cannot be, for when the soul first entered this existence, it had no Karma.
What again do you mean by “the all-veiling Maya” or by “losing all consciousness”? The soul cannot lose all consciousness, for its very nature is consciousness though not of the mental kind to which we give the name. The consciousness is merely covered, not lost or abolished by the so-called Inconscience of material Nature and then by the half-conscious ignorance of mind, life and body. It manifests, as the individual mind and life and body grow, as much as may be of the consciousness which it holds in potentiality, manifests it in the outward instrumental nature as far as and in the way that is possible through these instruments and through the outer personality that has been prepared for it and by it – for both are true – for the present life.
I know nothing about any terrible suffering endured by the soul in the process of rebirth; popular beliefs even when they have some foundation are seldom enlightened and accurate.