So, let us read now this statement (The Synthesis of Yoga p.419):
“The individual being of ours is that by which ignorance is possible to self–conscious mind, but it is also that by which liberation into the spiritual being is possible and the enjoyment of divine immortality”.
This sentence wants to emphasise that individual is not an illusion. The individual like the Bhagavad Gita is saying that the jīvabhūta is Para Prakriti therefore and sanātanaḥ: it is an eternal portion of the Supreme. And if individual being is an illusion then, who experiences bondage, and who experiences liberation? If individual is nothing then who is it that becomes ignorant? Who is suffering? And when you become liberated, who becomes liberated? If individual is an illusion, then who becomes liberated? It cannot be the Supreme who becomes liberated because Supreme was never bound; it cannot be cosmic self who is liberated because it was not bound. One who is bound becomes liberated. Now, who becomes bound? One who becomes ignorant. So, Sri Aurobindo says: it is the individual, the individual being of ours is that by which ignorance is possible. The one who becomes ignorant is the individual. It is also that by which liberation into the spiritual being is possible, and the enjoyment of divine immortality. Who enjoys divine immortality? It is the individual who, having gone beyond ignorance enjoys immortality. Therefore it emphasises that individual is not an illusion. Ego is illusion but not the individual. This is one of the fundamental principles of the Bhagavad Gita. There are many theories which believe that individual is an illusion, but Bhagavad Gita’s teaching is that individual is sanātanaḥ aṃšaḥ, it is the eternal portion of the Supreme; and sanātanaḥ means eternal, it is not whipped out.
Now, Sri Aurobindo will explain:
“It is not the Eternal in His transcendence or in His cosmic being who arrives at this immortality; it is the individual who rises into self–knowledge, in him it is possessed and by him it is made effective. All life, spiritual, mental or material, is the play of the soul with the possibilities of its nature; for without this play there can be no self–expression and no relative self–experience. Even then, in our realisation of all as our larger self and in our oneness with God and other beings, this play can and must persist, unless we desire to cease from all self–expression and all but a trance and absorbed self–experience. But then it is in the individual being that this trance or this liberated play is realised; the trance is this mental being’s immersion in the sole experience of unity, the liberated play is the taking up of his mind into the spiritual being for the free realisation and delight of oneness. For the nature of the divine existence is to possess always its unity, but to possess it also in an infinite experience, from many standpoints, on many planes, through many conscious powers or selves of itself, individualities—in our limited intellectual language—of the one conscious being. Each one of us is one of these individualities. To stand away from God in limited ego, limited mind is to stand away from ourselves, to be unpossessed of our true individuality, to be the apparent and not the real individual; it is our power of ignorance. To be taken up into the divine Being and be aware of our spiritual, infinite and universal consciousness as that in which we now live, is to possess our supreme and integral self, our true individuality; it is our power of self–knowledge.
By knowing the eternal unity of these three powers of the eternal manifestation, God, Nature and the individual self, and their intimate necessity to each other, we come to understand existence itself and all that in the appearances of the world now puzzles our ignorance. Our self–knowledge abolishes none of these things, it abolishes only our ignorance and those circumstances proper to the ignorance which made us bound and subject to the egoistic determinations of our nature. When we get back to our true being, the ego falls away from us; its place is taken by our supreme and integral self, the true individuality. As this supreme self it makes itself one with all beings and sees all world and Nature in its own infinity. What we mean by this is simply that our sense of separate existence disappears into a consciousness of illimitable, undivided, infinite being in which we no longer feel bound to the name and form and the particular mental and physical determinations of our present birth and becoming and are no longer separate from anything or anyone in the universe.”